I just wanted to write up what a great job you are doing, that your effort is most certainly appreciated, and I'm glad you haven't left us old school gamers at the mercy of bootcamp/Windows
You never were
at that mercy. SDLMAME runs terrific on OS X (it's a few ticks faster than MAME OS X due to the lighter-weight video path) and combined with MAMEPGUI has an arguably easier-to-use interface.
It runs slower in my experience. Some games don't run at all, while MAME OS X runs them just fine. As for MAMEGUI, because it's not a native OS X program, it's awkward and clunky, feeling twitchy and unresponsive. I really prefer native OS X apps. I know it's a lot easier to have cross-compatibility using things like QT, but the program suffers. QT only truly runs well on KDE. Even on GNOME it's clunky and slow. It really pays off to program for one type of OS... sad, but that's just the state we are in.
I'm currently using SDLMAME/MAMEGUI but would rather go back to using a Mac OS X based program (like Dave's). Not bashing the many people that put in great effort on the former, just my personal preference...
While MAME OS X doesn't have a sophisticated interface, it does have the listing to show only favourites. That's a huge plus since I probably will never play 80% of the roms out there. I find I don't need a ton of the options in MAMEGUI. It seems far too bloated for me. Some features are nice, but overall, I can live without them... Again, it's all personal preference.