Not to knock the work done by those porting it, but the Amiga emulator needs _lots_ of work. Runs about 25% speed in my experience. What happened to the Fellow conversion to C? That code base might be a good starting point. I'd have a go, but don't really have the time:-(
That said the GP2X is indeed fantastic. As is the GP32, thought most of the scene has moved on now. For those who enjoy Jay Miner's other creations try
http://www.scrameta.net for the Atari 800 emulator;-)
Thanks,
Mark