Hey Rick,
Check the final post by Luap in this thread:
viewtopic.php?f=8&t=673&p=4223&hilit=commander+shutter+canon#p4223Basically you are stuck with 1/250 for now but there may be a firmware upgrade in the future to support 1/200.
If you are lighting the scene totally with flash (no ambient) then it won't matter as the exposure is dictated by aperture and ISO and shutter speed won't play a role. If you have ambient mixed ambient and flash then your ambient will be off but not too much. I shoot a 5d mkII and I'm stuck at 1/160 so I just shoot, chimp, and adjust to taste. Hope this helps.