You've probably got more than needed. In such a venue I'd only use the 15 if it had a horn. I do 90% of the gigs I bring my amp to with a Peavey TNT150 (with an added piezo tweeter). If I foresee being standing too far away from my amp (I like bands setting up close together even in big stages -more on this below-, but that's not always possible) I bring a second TNT150 I enslave to the first. My head rack rarely leaves the practice space (only for gigs where somebody else shares his/her cabs) and my cabs haven't left the place in years. I think the need for more or less amp capacity is more a question of how close the band sets up (and indirectly how close everybody is to their amps and how complex monitor mixes get as you stand further apart from your bandmates) than a matter of how big the venue is. If there's a PA (something that should happen on any >150ppl club) the band can have a really pleasant, tight sound experience and look good by standing close together (I much prefer to see/feel a band as the core of the stage than to see them spread apart, with wireless units you can still be able to fill the whole stage). And the benefical effect of it is also less volume needed. All this if you don't go crazy on the monitors. Then again, no need to ask for every single cowbell of the drums to show up in your monitor mix, start with the voices, exactly as you'd do at rehearsal, hearing the rest of the band from their instruments/amps. That's any band's most "familiar" scenario, and really works live. This is some corporate party at a country club house a couple years ago with this very vocal punk group I have (in the vein of Me First & the Gimme Gimmes but covering old latin hits). Just as we did soundcheck that afternoon (on a small PA only for kick drum and vocals) neighbours started complaining so it was "as quiet as you can do it". So we did. The drummer loosened up and we dropped the volume in our amps and PA to a point where we could even chat while playing. Guess what? It sounded TIGHT and clear, nice for the customer, nice for the neighbours, nice for everybody's ears, everybody could hear everything precisely and we performed great. Not a big stage or venue, of course, but I've tried this playing for 30 and for 100 thousand people and it keeps proving effective. I understand a loud PA usually plays tricks on your onstage sound, even if you're careful with onstage volume, but once again, the best thing to do to overcome that too is setting up your gear real close center (always better than standing 5m apart from the drummer you desperately need to hear -or your own amp for the case-). I'm all for it as the remedy for many forms of onstage sound chaos, AND it keeps you from hauling excess gear of which output gets mostly lost in the air.