It would be nice to see these cases tested with hardware that they were designed for. I suspect the landscape would change significantly if these cases that were designed for water cooling were tested with a water cooler.
The noise and cooling performance would obviously change, but just as important is the difference in installation convenience. Installing a water cooling setup is quite different than installing a single tower air cooler, and there are significantly more issues that could come up.
Tom's Hardware has plenty of information on closed loop water coolers that would be suitable for such a test. The price difference between the cooling systems could easily be accounted for in the value comparisons.
Regardless, I seriously question results that are derived from a setup that you'd never actually use.