I've used Metz AF-1 48, which are comparable in power to the Vivitar 283, but for some reason these were never powerful enough for candid shots. The good thing about radio controlled off camera flash is that my camera rig (EOS 3, RZ67) grabs a lot less attention than one with flash or even with a large diffuser.
One big concern I still have is the discrepancy between what looks normal to the eye vs. what looks normal in a photo (think mid day sun). Since the walls are substantially brighter than the floor, the light could be quite directional from above. I guess it's time to simply try it and if the issue pops up, put a bright blanket on the floor.
The light bulbs are 240W (6 x 40W) halogen lights, yet I only get 1/80s at F/1.2 and ISO400 before color temperature correction (which would cost an extra 2 stops). Doubling their power somehow would likely destroy the room light within minutes and still require too large apertures for group shots. If they were regular light bulbs, I could replace them with these funky 50 Ws strobes that have the same screw thread as a regular light bulb.