I'm currently looking a lot at the Rivera Chubster series; there is a 40W and a 55W version - these should be more than giggable, right? Even in a 1x12 combo?
Definitely!!!
I own a 55w Rivera R55 (1x12), and it's very loud - the dirty channel struggles to get above 3-4 without hurting people, and the clean rarely gets above 5.
I have also used a Palmer PDI-09 speaker emulator on the line out, and send this to the PA at gigs, although if I'm honest I prefer the sound of an SM57 in front of it - the speaker emulator is good, but it just doesn't sound close enough to the real speaker in the amp. I'm also just about to add a 2x12 extension cab into the lineup, but more for added spread and depth than volume (of which I definitely don't need any more). However, I've used the R55 on its own (no added cab, no mic, no speaker emulator) at a fair few gigs and it sounds great on its own. Definitely no worries with either the 40w or 55w Chubster in terms of volume available,
Out of interest, I originally planned to buy the 40w Chubster, and played a couple at the time. They're great amps, and the added depth of the cabinet makes it sound alot bigger than a 1x12. I would have bought one, but the week I planned to do it I found the R55 on ebay, and got it for £650 in mint condition. Definitely the luckiest I've ever been when GASing :-)
Hope some of that helps,
Jordan.