To be honest there isnt a great deal of difference in the temperature which way you place the PSU - I tried both to get the neatest cabling solution, and using temp probes monitored the results. Worst case scenario was 2 degrees - in a heated room.. so you should be fine either way up. I settled on fan up
Interesting study... I've always been a believer in having the fan facing up so it sucks air in and exhausts it out through the PSU.
@OP: I recommend picking up an 8-pin ATX power cord extension to help with the cable management. It made a big difference for my Antec 1200 build.