I have been to Ken's place and he had an couple of ICS guns on site. Side by side there was an extremely noticeable difference in external build quality and body set up. over all the SRC felt much more sturdy the upper and lower receivers meshed perfectly with no gaps or noises when moved. The two ICS guns had a little more play in this area due to the the joint between the two non metal components (the upper reviver is nylon fiber I believe). Both guns are realy sturdy But having the metal upper makes a world of difference if you have a slip and fall incident and adds weight and a stronger feel to the gun. The ICS has an extremely easy to field strip and do spring changes because of the 2 part gear box (a single pin holds the tow parts together). This makes it ideal if you want to swap out the spring or full upper gear box making switching form indoor to outdoor fps a breeze. To take down the SRC you will have to almost fully disassemble the gun (remove the two body pins with hex key retainer screws pins and the stock i believe feel free to correct) ICS boasts the strongest lower receives however the SRC receivers were as good if not better than the ICS receivers and the matte sand blasted finish looks incredible.
It depends entirely on what you intend to do with the gun. If you intend to use it as an indoor and outdoor gun, and don't mind sacrificing a little bit of wight and body strength go ICS. If you don't want to open up your gun often or at all or mind screwing around a little bit to get at your gearbox than SRC is BY FARRR the best way to go.
Just my two cents