Dual fans never seem to help these units and if I do add another fan it introduces an extra variable since not all fans are created equal. If anything, using this inside a case with side panel fans and better airflow would have better results. The chassis I use, the Zalman GS1000 has no side panel fans or front panel intake fans as well so it is not as efficient. I use this chassis as it keeps the playing field level and forces the cooler to cool the CPU and stops the chassis fans from adding extra cooling that others may be able to give.
I can understand that from a review standpoint it is probably best to test with the stock configuration to keep things fair. I have an Asetek cooler (similar to the H50) and it got a couple of degree temp drop off adding a second fan. It was about the same drop as adding a shroud to a single fan. What I really like about these small water cooling setups is how it clears the space around the CPU and RAM. Tower coolers have a tendency to crowd the RAM slots.