Hmmmm I can only get to about 1/250 or less using my 200 1.8 lens (at 1.8) and ISO 800 (on my MKII). The combo takes amazing images but I obviously get some foot blur with that ss. I can go to ISO 1600 but the noise is not acceptable to me, at 800 it's pretty good. I wouldn't think the shows I go to are darker than yours....

I want that MKIII!!!