If popularity was the main ingredient of creating great gym equipment, then Marcy would win hands down. They make more home gyms and fitness gear than most of the industry put together.
But having tested over 40 Smith machine systems, I can tell you that popularity definitely isn't the best indicator of quality. In fact, hype is often used to cover up a lack of quality, based on my findings.
But does this apply to Marcy?
I scoured through countless Marcy MP3100 Smith Machine reviews to find out.
Skip to the conclusion now if you want to see the results.
The Marcy 3100 Platinum Smith Machine combines over five workout stations into one compact gym system. As the name suggests, it comes with a Smith machine. But you also get a pulley system, pec deck, preacher pad, leg developer and an adjustable bench.
The only thing missing is a free weight rack.
Add in the pulldown bar, press bar, ankle strap and single handle, and it's clear that the Marcy Platinum MP 3100 offers enough variety for you to pack in your gym membership. You'll have to buy your own weights, but aside from that, you have virtually everything that you need to get a full-body workout from home (and thus save a lot of time).
But if you have no idea where to start, then you'll find the workout chart with 24 exercise demonstrations helpful. It's a nice touch that's useful for learning the proper form, which can help you to avoid injuries in the long run.
The frame of the gym itself is made from 14 gauge steel, which is very much the industry standard for home gym equipment.
Some products use sturdier 11 gauge steel, which is great if you're serious about your training. Yet for those who just want to get in a quick workout without the hassle of driving to the gym, a workout system that's made from 14 gauge steel is more than adequate.
Likewise, the unit comes complete with adjustable pop-pin safety catches, which are a must-have when you're lifting without a training partner. The convenient pop-pin design also makes it stupid-simple to change the safety catch height, which is particularly useful if you like to train at a high intensity.
The Smith machine has a 135kg weight capacity and is slightly angled to promote a more natural lifting motion. This slant probably won't make much difference on something like squats. But for bench presses, on the other hand, it can make you stronger since most people naturally arc the bar backwards a bit as they lock out the rep.
Marcy also includes adapter sleeves so that you can use both standard and Olympic weight plates. This versatility is useful when you're shopping for new weight discs since you're not restricted to one particular diameter.
The bearings are made from ultra glide bushings. And although not as smooth as linear bearings, they're still suitable for home workouts, where you don't generally expect commercial quality.
The Marcy Platinum MP3100 Home Gym comes with two cable stations—an upper and lower pulley—which each have a 90kg weight capacity.
You can use the higher pulley to build a wider back and bigger arms by doing exercises like lat pulldowns and triceps pushdowns.
Likewise, you can beef up your biceps and broaden your shoulders with the low pulley by doing bicep curls and lateral raises, among a host of other exercises.
You can also sit on the floor and do cable rows with the low pulley. However, since there's no footplate, it might hard to maintain your stability (and thus lift heavy).
One of the main gripes users had was the pec deck. It didn't start producing tension until they were halfway through a rep, which prevented them from getting a full stretch.
Since the weighted stretch is so essential for muscle growth, this might be a deal-breaker if building a bigger chest is a priority for you.
That said, if you're somewhat mechanical, then you can shorten the cable yourself to increase the consistency of the resistance. Personally, I wouldn't attempt this, because I'm pretty sure that it'll void your warranty.
The adjustable bench is the lifeblood of the Marcy Platinum 3100 Smith Machine. It measures 175cm L x 74cm W x 126cm H and houses the preacher curl and leg developer attachments. Also, it functions as a standalone bench, which opens up many more exercise possibilities if you have some dumbbells handy.
You can adjust both the backrest and seat over 5 positions. Namely, these are flat, incline (multiple), decline and upright. Naturally, this enables you to build a more proportional physique because you can hit your muscles from different angles.
Despite being made of comfortable 2.5" thick upholstery and supporting users of up to 135kg, the bench has one major flaw: its leg developer has a tiny 45kg weight capacity, which is hardly enough for lying hamstring curls.
That said, the preacher pad does have two height positions. So if you're focused more on your upper body than your legs, then this home gym might still be a decent option.
As I mentioned earlier in my Marcy MP3100 review, you get a good amount of accessories with this home gym (much more than the Marcy MD 5191). The package includes a pulldown bar, straight bar, ankle strap and d-handles.
Collectively, these gym attachments enable you to train your full body, which makes the MP31000 appealing if you're on the market for a home gym rather than just a Smith machine.
You also get an exercise chart with 24 tutorials to help you learn the correct form. Aside from helping to reduce injuries, the workout poster enables you to get faster results because you'll be more inclined to use a full range of motion if you know the proper technique .
The Marcy MP3100 Smith & Bench is constructed out of heavy-duty 14 gauge steel and comes with a powder coat finish. This durability enables it to withstand wear and tear and also accommodate users of up to 135kg.
The cables are similarly durable. They have a 907kg (2000lb) tensile strength, which is the amount of pressure that they can withstand without snapping .
Likewise, the 4" nylon pulleys have sealed ball bearings to minimise friction, thereby enabling the cables to glide smoothly. That said, you'll still need to lubricate the components with some WD-40 to keep things running smoothly.
The cage itself is slightly slanted. This design choice might seem weird to some, but there's a method in Marcy's madness. Since no human lifts straight up and down, the slight angle produces a more natural range of motion.
Now onto the all-important Marcy MP3100 dimensions.
The Marcy MP3100 Smith Machine with Weight Bench package measures 230cm L x 200cm W x 210cm H and weighs 108kg.
Still, the MP 3100 is pretty compact when you consider how many pieces of gym equipment it replaces. Plus, the off-the-floor base makes it nice and stable, which is useful if you like to lift heavy.
Just make sure that you leave some space between the back of the unit and the wall so that you can load weight plates onto the pulley system.
Here are the max weights for each station
I spoke about this in my Marcy SM-4033 review, but it can't be said enough: Safety is especially important when you train by yourself at home. Having good bar catches could be the difference between a new personal record and permanent injury. So it's vital for your wellbeing that you don't skimp on quality when you're shopping for a home gym. 
The MP3100 comes with pop-pin safety catches that are fully adjustable. This adjustability enables you to set a hard limit on how far the bar can travel on virtually any exercise.
However, since the max bar weight is only 135kg, I'm not sure how durable these safety catches are under substantial impact.
The Marcy MP3100 manual labels the parts from the hardware pack at the start so that you don't get confused between bolts and washers of a similar size.
There's both diagrams and textual instructions on every page (as well as a ruler), which helps you to distinguish between small parts.
It comes in 2 boxes, and you're looking at around 5-7 hours to get the job done. If you only want to spend a few hours setting up your home gym, check out my Marcy TSA5762 review or keep reading for an even higher-quality alternative.
The Marcy MP31000 is a decent home gym. It replaces over five pieces of workout equipment and has plenty of accessories to get you going.
I also like that it comes with a detailed exercise chart, which is particularly useful for helping beginners to minimise their injury risk by learning the proper form.
However, there are a few major flaws that prevent the Marcy 3100 Smith Machine from getting our stamp of approval.
One, the weight capacity. The leg developer has a 45kg maximum weight rating, which is too low for anyone past the novice stage .
Also, the bearings are plastic rather than steel. This design choice gives the unit a cheaper feeling and also makes your exercises more prone to interruptions from friction, which is incredibly frustrating.
Out of all the products that I've tested, the Body Solid Smith Machine PSM144X is easily the best value for money—and it also has incredibly fluid resistance. Even at extremely heavy weights (for me at least) my reps felt smooth and unrestricted, which isn't surprising considering that it can hold up to 181kg on the bar.
Body Solid also lets you customise their Powerline Smith Gym with more than 5 attachments. This personalisation means that, unlike with other home gyms, you only pay for the workout stations you actually want. Plus, they offer 3 money-saving package deals so that you can grab a full home gym without paying the usual rate.