I'm considering taking on a small Tae Kwon Do tournament with a Mark III, 20D
and one main lens. The lighting should be good enough to get 1/400 at ISO1600 f2.8. I was wondering if the 24-70 f/2.8 is as capable as the 70-200 f/2.8 for sports action? I've shot some dance with the 24-70, but I'm just not sure it's as good as the 70-200.
However, the 70-200 is a bit long and Tae Kwon Do doesn't give much room
with parents and refs crowding around the ring (comprised of floor mats).
Either lens will be capable for sports action - my typical indoor setup used to be 70-200 on one body and 24-70 on the other. But given that you are bringing two cameras, why not just stick the 70-200 on the mkIII and 24-70 on the 20D?