I'm mining on Pi, and you're right to be concerned about USB issues. For starters, a single Pi it won't mine more than 12 block erupters...
It certainly works, but I'll be getting a Beaglebone Black for my next project - I only hear good things about it.
Oh really? 12?? That won't work then. Perhaps connecting to a real computer is the only way to go then. Perhaps I'll have to look into a mini-itx based ultra-efficient PC for this task. I've seen android miners as well, but unsure about their capacity =(