Hi all, I do a lot of gig photography, with both in low light and fast changing coloured light set ups, I'm usually having to run nearly wide open (lens wise f1:1.2 to F1:2.8) and at 800 to 1600 iso, with continuous advance drive mode to get good usable results. 
For me one of the major benefits of DSLR is the ability to keep a check on what I'm doing. I agree not after every frame, but when the action goes off a bit i.e. between songs, I have a quick review of what I've got. It's still pretty hard to see the quality on the camera LCD screen, but it does give you a feel for where you are in terms of the images you've captured already. Checking histograms doesn't really apply here, we're talking dark, low light stuff here; you know every thing will be bunched up on the left. That is except when some bugger of a lighting engineer has his wee laugh and damn nigh blinds you with the odd one million watt white spotlight from the stage out to crowd. 
In terms of power requirements, I run two batteries in the camera (body and grip) with spares in the Crumpler, same with memory cards. If this is your lively hood, these are the cheap consumables like film used to be. It is not worth skimping in this area, have loads of both, no excuses, just get the stunning images.
