The noise of 500 people in a typical club requires at least 1000W of PA to get vocals over, and that doesn't include subwoofers. Unless you're playing a mellow folk for a mormon convention, PA support is absolutely necessary. On NYE I'm playing a rock gig in a 175 cap room and I'm bringing a 2600W PA. Granted I've played bigger rooms without PA support for bass, but for that crowd any less would be shortchanging the venue. It's gonna be nuts. Crowd noise is just as big a factor as room size for power requirements.
I'm right about at my weight and size limit with my current setup but was looking to maximize. I've tried a bunch of cabs and am back to my Bag End's. I have a line on an Epifani UL 310 series 1, size and weight fit but it's strengths seem to lie in the standalone-ability, rather than adding to my current 4 ohm cab load. The Walkabout can do 2 ohms tho, but 8 + 8 + 3.5? Wuzzat?