I have an ics 45 c-15, which comes with the full stock. The plastic lower worries me, when i first the gun, after looking at it really carefully i realized that with the battery in the stock, the weight causes the lower to flex opens up a 1mm gap at the vertical crease between the upper and lower. And not too long after I got the gun, a crack developed at the rear body pin hole, I've also noticed that that a crack also developed at a pin hole for the trigger guard. Keep in mind that I take good care of and don't abuse my gun.
Otherwise I've had no problems with the internals, and its a pretty reliable gun. I'd recommend the cansoft ics m4's, just not with the full stock.