Go to head-fi.org's forum on full-sized headsets for a search of opinions. I recall that the dedicated closed-ear crowd over there really like the HFI-2200 and most Ultrasone designs in general.

http://www.head-fi.org/forums/f4/

Personally I'm not a big fan of closed designs, having been force-fed open-aire Sennheisers for most of my adult life (ok, kidding about the force-fed part...but they ARE my preferred brand of choice). I have a pair of Ultrasone HFI-700 that I just never warmed up to, in part because they were bloody uncomfortable for me but also the dense, clouded sound inherent with closed cans is awfully hard for me to call great-sounding. As for the Phiaton, maybe I'm showing my age but oxygenated-blood red cans just are tad bit much for me and my older-fogie tastes...and that I have zero experience with the brand (they're from Korea, right?), but off the bat from your numbers they slightly over twice the efficiency than the HFI-2200 is.

Ultimately, if you haven't done so already you should try to find a reseller locally to you and see about TRYING each unit. Let your ears do the deciding and forget about the specs, especially since there doesn't seem to be much in the way of overlapping measurements.