Just browsing around the net and decieded to check out the Lytron site,
http://www.lytron.com. Well I must say if ever there was a template for which the capabilities of watercooling blocks and heat exchangers should follow I think they hit it square on the head.
For example here is the page to their top Cu heat exchangers follow the link here
http://www.lytron.com/standard/he_6000.htm to the 2003 catalog section. On it there's a pdf file under showing the different models and the performance charts for the models. I appologize but in order to see them Lytron wants some info on you, trust me it's worth it to enter it!!

Included are Q/Initial Temperature Difference charts for all radiators which are across realistic flow rates and CFM values, as well as coolant pressure drop curves and air flow pressure drop curves.
If you follow this link here
http://www.lytron.com/standard/cp_extended.htm to the 2003 catalog setction you will find their "cold plates" or as we call them waterblocks. Once again they include just about everything you would want to know about their waterblocks on the PDF.
If you are a regular there and I just wasted your time, I appologize but I thought it was good and wated to share with everyone. Let me tell you, it sure would be nice if the smaller companies would post something to this effect instead of just letting everyone guess and/or base their decision on looks and marketing. It is sad, but I bet we will never see something like this in the "hobbiest" world of CPU watercooling.
EDIT: I guess everyone wants to see my girlfriends boobies, so here ya go...
EDIT 2: this is my other GF Christina Ricci, aka Wednesday from "The Adams Family"