[pHaestus]

It's a huge expenditure of time as your "system testing" audience immediately demands a huge variety of combinations of pumps, radiators, fans, fittings, other blocks in the loop, ad nauseum. You cannot easily measure water temperature or flow rate without introducing at least some restriction (even if it's just a pvc cross)... it would be incorrect to reference Heisenberg but there is I suppose a correlary.

In my opinion this isn't the sort of testing approach that anyone with a technical background is going to find very rewarding or interesting for long, and someone without technical skill is going to do it so poorly as to make it useless.

Now having said that, what of kits constructed by a mfgr after extensive R&D? We as a DIY community could I think learn something from examining how the individual parts come together to make a whole cooling loop. The compromises between size, noise, total cost, and performance that mfgrs make are often somewhat different from my personal choices; how much different are the outcomes? THIS is a question worth throwing some time into looking at (and I have a German and Swiftech "kit" that will be tested soon as well as my personal cooling loop).