As you are already aware, screwy lighting, changing colors, changing intensities, pose significant problems in shooting concerts, or, in my case, church activities.
It's a big-time 'battle' with the exposure triangle. Paramount, of course, is stopping subject (and yours) motion. Having a lens with Image Stabilization is good to have, but not essential. The tradeoff with non-IS lenses is you'll need either a faster shutter speed and higher ISO to stop camera motion. Of my current 4 lenses, only the 24-105 f4L has IS. I'm fortunate enough, though, to be able to drag around a monopod with ballhead while I'm shooting, to make up for the lack of IS. In the 4 day church event shoot I just finished Sunday, I found 1/200 gave the most non-blurred subject results. 1/160 did well, but not as successfully as 1/200. I tried 1/125 with the 24-105, but 1/125 wasn't successful at stopping action during the bell choir concert. So, limited pretty much to 1/160 and 1/200 shutter speeds, I had to decide what ISO and apertures to use to get what I wanted. In a couple of very low light situations, I was near shooting wide open at f2.8 and ISO 10000. But most of the time I was in the 1/160th and ISO 4000-5000 range...at or near wide open.
In looking through the results of about 2500 shots, I think next time, I'll try Tv at 1/200 and let the camera figure out what combination of ISO and aperture it wants...limiting ISO to 8000. That way, I won't have throw-aways every time the lighting changed. But then, when I want to get a wider DOF than 12" or so (from 30-50 feet away), I'll switch back to manual and get what I want. Bottom line...while f4 lenses and slower ISOs (camera limits) will get some decent results, having the right 'artillery' greatly increases the number of shooting options and improved results.
Here's a couple of results. The first is with the 135 f2L at f2.5, 1/160 and ISO 8000. The second, the 'magic drainpipe' 80-200 f2.8L, wide open, 200mm, and ISO 5000.

