Background is that three times each year I photograph and video my daughter's ballet performances. I can't get close enough for normal primes, do in stuck with tele zooms. The challenge for me is freezing motion. Most pictures are blurry. Only a few are useful and I get them by shooting on H, timed for turns and positions where I know motion will slow a bit. I'm sure skill has something to do with it, but I can't get a SS faster than 125 and that is rare. So somehow it needs to be easier. I use my 50-200 SWD. Even when zoomed out and shooting at f2.8 I can't get SS up high enough. I limit ISO to 1600 due to IQ above. Sothe question is how can I best get more speed? A 35-100 f2 would be a potential option. I'm not sure a 40-150 pro would be adequate. A canon 70-200, 2.8 with a speed boosted AF adapter might work. I'm afraid that a FF might be better than any MFT option but I hate to go that route. Some of you must have experience with this scenario. What was your solution?