I'm really pleased with the Roland Cube 100 I just snagged on the cheap. I've used it for a few rehearsals and a couple gigs with my band, the Inactivists. That band consists of bass, drums, guitar, ukelele, theremin, trombone, vibes, congas, sometimes accordion and sax. Everything runs through an amp or the P.A. Vocals all around if we have the inputs at the board. Not a terribly loud band, but not a folk house/coffee shop band either, by any means. A few fairly aggressive tunes even...
The Cube is completely sufficient for a group like that, who have pretty good self mixing skills, when jamming in the basement.
Both of the gigs I've used it on have been outdoors. One was a big Denver event called the Peoples Fair. Typical outdoor, fairgrounds type of stage setup. The amp provided me with a great stage monitor and a line to the board for the folks out front.
Second gig was a backyard patio party sort of thing. I set the amp up next to the house, no mic or D.I.. It was plenty for that environment.
Not sure I would be confident using the Cube at a medium to large sized dive bar with no possibility of reinforcing the bass with a direct out front. I might actually try it in just such an environment soon, but I'll definitely be bugging some people I trust to tell me how it sounded in the room. I think it could struggle a bit there.