I've got a Raspberry Pi set up emulating a bunch of NES and SNES games like you plan on doing. I had to overclock it pretty far to get SNES working at all, and

I've got a Raspberry Pi set up emulating a bunch of NES and SNES games like you plan on doing. I had to overclock it pretty far to get SNES working at all, and higher-end games (particularly those using the FX chip like Star Fox) really struggle. The emulators can't really use the Pi's better video card as far as I know, but I think the stronger CPU on the BeagleBone may give it the edge.