I have a GP2X Wiz and my experience with Wiz fMsx is bad:
*Do not load all the discs images
*The sound is good but the volume is very low
*If you put the emulation at 60 frames per second, the emulation is fast and the music run fast, why?
*Bad screen scale
*Screen 7 do not look good (not a smart scale to show the better definition)
*MSX2+ emulation lacs of the screen6 logo at boot and Horizontal hardware scroll.
*If you choose the high sound volume the emulator has constant clicks.
On PSP is the same buggy emulation, I am waiting to PSP Vita, this console has enought power to run BlueMSX, a much better emulator.