"There has been a lot of controversy over VFC scar's in the past few years. Frequent topics are the motor frying out, poor stock wiring, self-shimming gears, crappy proprietary hopup unit... and if you have done the research, you know the rest. While these are issues on older scars, I am glad to say that recent models seem to fix some of these issues.
Practicality: The big question is: Why scar over M4? The scar has a very unique look to it, and is largely a love-it or hate-it gun. Chances are that if you are taking the time to read this, you like or accept the style. As far as egronomics go, the scar stock is superior to any standard M4 stock as it has an adjustable cheek rest, 6 extendable positions, folds to the side, and has a curved ruberized butt pad. As a side note, just know that this is VFC, so when you fold the stock, NO WIRES!!! The gun is covered in rails, so it has more room to add toys than most stock m4's. In my opinion, the biggest advantage a scar has over an m4, apart from its looks, is its light weight. The nylon fiber lower reciever really does help to keep the weight down and minimizing weight is a good thing, especially if you plan to move around a lot. The problem to all this goodness- everything external, including the pistol grip, is proprietary (except the flash hider, 14mm ccw). If you break it, your gonna have a bad time finding replacement parts. The other bad thing is battery storage. The maximum you will be able to fit comfortably is a 2200mah 7.2 lipo or barely a 1600mah 9.6 NiMh. Not too bad for lipo users, but a breaking point for most of those stuck with NiMh. As far as internals go, pretty much completely v2 comptable so if anything breaks here you are fine for replacement parts.
Quality: Externally, its a vfc. nuff said. Absolutely fantastic build quality, paint simply will never scratch off and nylon fiber can easily be mistaken for metal. Internally, not bad. Wires are somewhat thin but not as bad as some people make it seem. Solder on a pair of deans connectors to save space in the stock. The motor is a crappy, nondescript plain high-speed motor. I got 1000+ rounds out of mine before replacing it with an a2, nothing went wrong, i just prefer a snappy torque motor over a high-speed space heater. Gearbox wise, 6000+ rounds and still no problem with self-shimming gears, so dont worry. Only bad part - HORROBLE stock hopup unit. It will rattle, shake, UNWIND ITSELF AS YOU SHOOT, and will not accept aftermarket buckings.
Upgrading: The first thing to go is the hopup. Everywhere you look, everybody is going to tell you that you can't put a different brand chamber in a VFC scar, its a propirietary hopup. WRONG!!! A standard, 2-piece m4 hopup unit will fit like a charm if you trim down the "wings" on the side to the same length as the stock "wings". The upper part of the 2 piece hopup unit can be found here on evike. The ones by AIM and JG are available, although I'm not liking the AIM, its worlds better than the stock unit with a lonex 70 degree bucking. Internally, change out the motor for a lonex a2 titan and leave the gearbox alone. Put on a pair of deans connectors and you are good to go.
Stock- poor trigger response, poor accuracy, average rate of fire.
With suggested upgrades (~$70) - Lightning trigger response, great accuract, slightly above average rate of fire.
Verdict- an excellent gun for those who like the style and like to tinker with internals a bit to claim a gun as their own. If you can't change a motor or swap a hopup unit, go with a kwa M4. 9/10 for those that can tinker, 5/10 for those who cant. Dealing with the stock hopup is a nightmare, if you cant change it or pay someone else to do it you are better off getting another gun.