Well,kinda a loaded question.I'v had my ICS for almost 4 years now in an up-graded state with no big problems.As for hard to get parts,alittle! But there are not many to worrie about,you can convert to a normal hop-up by mod'ing a normal one witch only leves the anti-reverse lever and mech-box shells.I have regular Systema gears and a few of my uppers have regular pistons,springs,guides,tappets.As for how stong,well I'v rolled on top of mine durring a game and it's still going lol.
Another thing I guess would be the cost of Mag's,from what I'v seen the KWA's are alot more for them at the moment.Not sure if thats an issue for you as any one else that has a PTW will tell you that it's not that big of a deal as once you have them you have them right! Sorry for the long post! Just my opinion,I'm all for the ICS,good luck with whatever you go with
