Its always worth looking at custom too, I know a kit always seems much easier because it is but you don't necessarily get the best mix of components. For example if I were looking for performance I probably wouldn't pick the swiftech rad or block in that kit.
Something like a thermochill PA120.2 and a Swiftech Apogee GTX or Dtek Fuzion coupled with a Laing DDC 12v pump (which is much smaller and quieter than the one supplied in that kit) would really be about as good as it gets and probably not cost much more.
There are no compatibility issues with pretty much any watercooling stuff, the only thing its good to keep constant is the tubing size.
Ask lots of questions on here and you'll get lots of answers