What will run on the 256MB Version
What will run on the 512MB Version
And what will only run on the 1GHz Version
Just about everything will work fine on the original 256MB version. They overclock happily and safely to 1GHz (or thereabouts). All Pandora developers wish to fully support this version as much as possible. Most emulators and games run perfectly, at full speed.
The 512MB rebirth has extra RAM (only) and so can multi-task a little better. It may run huge bloated apps such as Firefox and LibreOffice a little better. As far as I know, no Pandora games or emulators need the larger RAM, so there is no advantage for gaming.
The 1GHz version has 512MB RAM and a higher clock speed, can overclock to 1.2GHz, and the GPU is faster. It will run the most demanding (or least optimized) games, apps, emulators faster. Android, DraStic, PPSSPP, Aquaria will work better. Many DS games are still not playable in DraStic. It can't sensibly emulate PS2 or Wii or Windows XP, can't play Crysis.
In short, every Pandora software works on any Pandora, but the 512MB can do multi-tasking / firefox tabs, and the 1GHz gives faster performance. Honestly there is not such a huge difference between the models, and they are all totally better than any other pocket gaming device.
The original Pandora with DraStic (and overclock) can run some DS games at full speed (or close), on the original Pandora, including Mario + Luigi through time, Yoshi's Island, New Super Mario Bros (for many of the levels). It runs all the PSX games I tried at full speed. It emulates Mario 64 at full speed, Zelda OOT is a bit slow but playable. It emulates SNES, Amiga, etc at full speed. My awesome game runs at full speed, 60Hz even
Any Pandora offers unlimited hours of pocket retro and homebrew gaming, hifi audio, linux dev tools! and is fully elite.
You can tell I like
Pandora, since I write too much about it.