Well my watercooling has been through SocketA, Socket478, Socket754, now Socket939 and the cpu part's retired because i've got Prometeia now, BTW i had a very cheap and crappy waterblock the Zalman ZM-WB2, but with peltier chilled water, that didn't matter
The performance difference is very small between the RBX and MCW6002, and setting up RBX is a mess with all the y adaptors. I really like Swiftech's peltier products, they're of very high quality, in fact the peltiers they use are top notch and rarely ever malfunctions. So if you don't mind doing a little insulation work and have huge radiators, you could look into those, they can lower your temps as far as 20C below ambient temperature.