Hi Alex,
If working with computers on stage has taught me anything, it has to be *don't rely on them*. If you can avoid using computers onstage, that would be better. Have you considered using a loop pedal? That's what most guitarist and vocal artists are using for the kind of effect you're talking about. I'm not sure all of them will handle 10 simultanious voices though, but I'd definitely recommend using a pedal instead of a computer.
Here's a few suggestions:
Boss RC-20XL (handles 11 voices at once)
DigiTech Jam Man Loop
Boss RC-50
TC Electronic G System Guitar Multi-Effects Pedal
Hope that was any help
