Christopher, I see no reason why you couldn't use Surface Pro 2 or 3 to gig, especially the 3, pricey though it is. There's some real power in those tablets.

For the foreseeable future, though, I'm going to stick with JamUp on the iPads. It sounds absolutely killer.

Today I bought an Alto TS-110A for multiple uses... monitor for band use, P.A. speaker for cocktails, and as an amp substitute for if / when I gig with a live drummer. It was surprisingly loud & punchy and sounded very good with JamUp running through it. I really have to stop buying things...