Obviously specs don't tell you everything. But in addition to noise, I'd consider speed (slew rate). That will give you some kind of indication of the amp's ability to keep up with the changing dynamics of the music and help create a solid, 3-dimensional soundstage.
As to the Oade mods, I seem to remember him posting a long while back that the mic in needed to be disabled for power reasons. I think the op amps he was using drew a lot more current than the stock ones, so rather than rebuilding the DC converter circuit to provide more current capacity, he disabled the mic-in section to save on power.
Which brings up the idea that in addition to noise, slew rate, and rail-voltage reqts;, you should also consider current draw when selecting op amps. For our purposes with field recording, it sure would be nice to use op amps that run on 0v and +5v (or even +3v) and have minimal current draw. That does narrow the field quite a bit though.