There's a reason we've always had SRC in the AEGII section. :p
I always wondered why that was....then I understood once I got my G36K. >.<
Their Gen 2s have a ton of off spec parts. The guns are assembled well, mine (Gen 2 SRC G36K) had great shimming and greasing was done fairly well. The majority of the internals are either average or low quality. Piston doesn't work well with other gearsets. (in fact it will strip) My SRC shell was just whacked, so aftermarket gearsets could not be shimmed in it properly. (I made a shimming error and broke the SRC spur gear, so I had to replace the gears)
I honestly hate their G36K. I should have just sold it and bought a JG. The externals are fairly nice, but the hop up unit is horrible and most of the parts are off-spec, making them essentially proprietary without modifications. I ended up using a lot of JG parts I had laying around because they gave better performance. I would rather have a JG G36K, even if the externals aren't as nice. I sure wish I had gotten a CA G36K..... The SRC gave me nothing but headaches.
If you leave the SRCs stock, they will be reliable. However, the performance (for their G36s at least) is average at best. Accuracy is meh, ROF is okay. I remember taking my G36K out on Christmas day, pulling the trigger and thinking, "huh....this thing sounds and shoots about the same as my E1 G36C."
I think one of the newer CYMAs would be better than the SRC. I think the only advantage the SRC would have is the fact that it might be shimmed and greased a bit better. As far as actual quality of the parts, I think CYMA wins.