I am a proud owner of one of the early models without a flu, it overclocks to 156 without problems though. I saw a flu recently and I say they are much better! Although the gp32´s normal screen is a lot better than the standard nintendo gba´s and provides a good clear view even in lighting-circumstances where my standard gba just is not usable anymore, I say go for a backlit version!
Get one of the 166mhz certified ones. You´ll be a an even happier emulator user that way.
the emulators on the gp32 use the same roms as the pc counterparts. some even support zipped rom support!
Cheers, Mark