I have a 2x12 (3/4 open back) and a 1x12 (also open back), and the Roadster sounds great with both. I use them for all types of music (clean, mildly dirty, full on metal).
Ideally, I would like to get a 4x12 in addition to what I have now. I tried the Roadster in the store with a 4 x12 and I think it
sounds just a bit more focused, but that is being really nit picky.
Bottom line: You really can't go wrong with either the 1 or 2x12 though, especially if you want to travel light, or setup a cab in another room for
recording, etc. I highly recommend both.