The M4 market is so flooded , they are all pretty much the same.
Thus the reason why more and more companies are offering different body syles, Zombie Killer, Special Forces, Silent abd Deadly and so on and on and on.......
All models have thier advantages and disadvantages,
TM, excellent GB´s, more spare parts than stars in the sky, easy to work on,
Plastic Bodies, Sometimes very unstable, over priced
ICS, Easy tuning on GB´s, Solid Bodies, Excellent Quality, Reliable
High End Tuning Problems, Limited in Spare parts ( Compatability ) Over Priced
CA, Cabon copy of TM with full metal bodies, all kinds of Spare parts, easily compatible
with other brands, Dissasembly can be tricky with some models, Way over priced
Now to the new generation of clones,
More and more of these companies have realized that there is a huge market for their guns, most are on along the same par with the big 3 but for less than half the price.
As far as SYSTEMA goes, I realy don´t consider this gun to be in the same League as the rest, it was designed for and used as a PTW.