I know I'm a little late to the party on this one, but having done similar work in similar circumstances, I figure its worth mentioning for anyone else with the same questions. I get everyone's paranoia about leaky alkys, but the reality is you chew through the batteries so fast that its a swap every couple hours or at least daily, depending on your setup. Yes using imbalanced batteries isn't great, but if you are pulling your "fresh" batteries from the same wireless pack, they should be close as long as your packs are wired as a single power supply and not something odd. (it happens) But there are plenty of times when the guy with the good light ends up directing traffic, or if you are at all in charge, its very helpful to be able to point stuff out at range.
A consideration to the techie that most others won't have is heat management, that light might end up on for very long periods of time, think like the search and rescue guys, less like EDC. So for your big bad throwers, that's a consideration. A light that has good middle mode characteristics is a better all-round than something that is just a spotlight (just get your LX guy to shine one of the movers where you want to look!) Bigger factors are flicker in the mid ranges and what it does for close work, there are a lot of lights that are just tiring to use up close, especially outdoors, and where there are bugs. The other hand is that in festival situations you can kiss your night vision goodbye, between the show lights, long days, haze and other factors, you will need more light than the average. To be honest I got by with my Fenix E11 for a lot of events, and the E21 did okay for the big outdoor ones, but I wasn't doing anything that huge. I'm thinking that a good thrower and a decently floody headlamp is a good combo, half the time the headlamp just rides around your neck anyway as a close up work light. (someone needs to make a better necklace light....)
It all depends on what you are doing, just sound, you probably don't need as much as if you doing stage and rigging, oddly I found I needed more light when I did lighting as I spent much more time with my night vision blasted. Anything doing pyro or similar, I'd be thinking about mining grade lights, limit your danger points, might not be needed, but you just never know. Back stage, backline, or management most of your stuff is close so having a good thrower on your belt is worth while, but you rely on your little light more, the big one is more for when things go a bit wrong.... Depends on your position, and your crew situation really. And if you are the genny babysitter, then a good reading light is all you hope to need!