Interesting, but no qualifiers. Were those both new fans? Difference in age? The collar wasn't sealed, and if you look closely, it looks to be a little unseated at the vortex side.

If he is running a new can fan vs an old vortex, the results are not really suprising, equipment wears out. Like maybe he is just in the middle of replacing 1 with the other? In that case, its old vs new. Not really the same comparison.

I'm not backing either result, just stating that this is a totally non-scientific test that could skew the results in either direction. Meaningless really.

My 2 cents
YBG