So-far on the native OS I've got CPS1, CPS2, GameGear, GBA, GBC, GB, Genesis, Lynx, SMS, NeoGeo MVS, NeoGeo Pocket Color, NES, PC Engine, SNES, Wonderswan, and the 2 types of built-in games. The 4 GB of space let me put nearly every good rom for all those systems on it at once. Aside from a few of the bigger MVS games, I don't really need more space on it. I expect the MiniSD card will have plenty of room for movies when I get the last of the games I want on it. Movie playback is really great on it too BTW - most videos don't need to be reencoded to play back smoothly - it even supports FLV Youtube format.
I just got the GP2X Wiz a couple of days ago too, and so-far I'd say it's only got a bit better performance. I don't think the extra money, size and weight make it a worthwhile investment pitted against the Dingoo as far as emulation goes. The one thing the Wiz has going for it is the ported games. X-Com, Abuse, Quake, etc. The thing is most of the homebrew stuff on the Dingoo is ported from PSP or GP2X sources so there'll probably be a lot more stuff showing up shortly.
Edit:
After looking up the incompatibility, it appears many of the crashes I've been having are the result of the different hardware in my Dingoo. There's already a fix for GNUBoy to correct the memory leak. Glad to see that the problems are being worked out so fast



