Kathy's point about using higher sync speeds for daylight portraits is one of my reasons for seeking a higher sync speed. Second, while it's true that flash is my main action-freezing mechanism in derby photography, I am still using flash to
complement, not
overwhelm, the available light. Basically, I fire flashes from the direction the players are traveling in order to give a greater sense of direction and speed. But my primary light source is not flash. That becomes obvious in certain areas. For instance:
Note the skater in green (Roxanna Hardplace). Her face is frozen and fairly sharp, but the parts of her body which aren't facing or covered by the flash are far less crisp. This shot was at 1/250sec, ISO3200, f/2.8. I would love to try 1/500sec, ISO6400, f/2.8, but none of my cameras allow that. My current setup is firing a pair of manual-power, max-zoomed hot shoe flashes across the track, which means that at the far end (about 25ft/8m backward), the flash power is less dominant as a light source. Extra sync speed would help freeze action in non-ideal areas. I've messed with wireless TTL to make up for this problem, but TTL becomes problematic when one is deliberately lighting a subject unevenly with fairly hard light.