I use an M300 and one or two 6B cabs depending on the gig. Sounds amazing - very clear and articulate - and it fills the room in a very natural, non-directional way.
A single 6B is fine in my roots acoustic band (two acoustic guitars and a keyboard through the PA, with an unmiked drummer), but for anything bigger I add a second 6B. I've heard the 12B is a really good single cab option, but that's pretty big!
I also have the two channel 100 watt Cub, and that is amazing for it's size.
Any questions, let me know.
Cheers
Gareth