I regularly shoot at 3200 in clubs, etc., with good results. What noise there is (and there's not a lot) is easily taken care of in LR. I've occasionally ventured into 6400 and definitely noticed the noise increase in the shadows, but NR and dropping the blacks a bit (which in most cases is what I want for these situations) worked out well.
I'd take a few quick test shots in the event space at something like 3200 | f8 | 1/125, look at the histogram, and if needed, decide which point of the exposure triangle you can sacrifice. Is noise, DoF, or freezing motion more important? Good luck!
One last point: I've been fixated on (lack of) noise forever and have decided to experiment with 12800 and 25600 at a (non-paying) gig I'm shooting tomorrow night, just to see if there's room for noise somewhere in my photographic life.