My GBA SP runs Yoshi's Island at 60FPS.
lol jkjk But seriously it would be cheaper for him to keep his o3ds and just get a supercard dstwo. Unless emulation on the 3ds alone is so important to him that he wants to spend 200 smackaroos vs like 40. My DSTwo can do everything the 3ds can atm including PSX using DS2Linux (but the framerate is bad and difficult to set up I'll admit). TempGBA is excellent and so is CATSFC.
The 3DS homebrew scene is still very young and would take a while for emulators to be refined. Which is why I suggest a cheap alternative until the 3DS homebrew matures in the meantime and would warrant buying a whole new console.
EDIT: Oh... Seems my memory has failed me. All the main emulators run well. But not consoles like wonderswan, or neogeo pocket/color, Pokemon Mini, atari 2600/5200...
But on the swap GBA/GBC/GB, SMS/GG, Genesis, NES/SNES, Atari 7800, Neo Geo, PE Engine/CD, Colecovision, x86, Scummvm all run pretty good.