I have shot audience and comedians in a comedy club about a half dozen times, and most of my setup is geared around that. I have used a Pentax M 50/1.7, Soligor 135/2.8, Rokinon 85/1.4, and Pentax DA70/2.4 with decent results. One of the people who I work with wields a Canon with Sigma 17-50/2.8 for stage shots at Rock concerts where she can actually walk on the stage while the musicians are playing and then a Sigma 70-200/2.8 for audience and when she can't be on stage.
In any case, the lenses that you are considering would work well (and are flexible for range) with your setup (especially shooting at 800-3200 ISO). If you know the event well enough, you can keep primes on hand to get those special shots that you've planned for.
Last edited by icywindow; 06-10-2011 at 10:40 AM.
Reason: Clarifying