The clearest demonstration I think can be found in OC's HSF and WB testing results,
here
As you can see, the best WC kit has a C/W rating of 0.23, the best WC block is rated at 0.19, where the best P4 cooler is rated 0.16 (@ 51dB) or overall best HSF on simulator 0.22 (74 dB).
Not entirely an accurate picture though, because a watercooled system can handle the peak loads a lot better (someone correct me here, if I'm wrong).
Hawkzx: this seems far too simple a project for a MS thesis. Can you elaborate? I would expect this to come from an engineering level study, not from a Master's.