OSX development sounds nightmarish (as well as time consuming and expensive).
All things considered, it's really not that bad. Qt takes care of 99% of the heavy lifting. The problem, of course, is that we're at the mercy of Qt's devs. From what I've gathered, they've tended to neglect Macs, probably due to minimal feedback from external devs like myself. Mac stuff tends to get moved around every now and again too, which is one reason why a small patch I've submitted to the Bitcoin core devs requires a convoluted path (i.e., it has to work for Qt4 and Qt5, and attempts at code optimization require three different paths).
Above all though, as far as new features go, I'd vote for BIP32 wallet format, Trezor integration and coin control with output separation. It doesn't strike me there would be alot of technical challenges with these, especially for coin control.
To me, Armory is still a power user app, however easy it becomes to install or how stable it runs on platforms like Macintosh. People don't choose Armory for an easy ride (and so it's not that well suited to Mac users anyway, at least until it makes more sense to devote the time to iron the wrinkles out on that port).
Don't worry, the bigger features are much higher on the priority list.
We're just doing our best to give some love to people using OS X. Besides, somebody really ought to understand Qt if it's going to be an integral part of Armory.