Currently using the FlexTT5 and AC3 from Pocketwizard in shooting Roller Derby. Really simple setup, 2 flashes (SB-800 & SB-910) and 2 FlexTT5's on Lowel UN-55 light stands at full height (about 8'). The lights have to be as high as one can get them to keep the shadows under control. The flash power was controlled manually with the AC3 unit and I adjusted as needed. Next time around will be trying CTO gels on the flash heads in order to get a better balance between the ambient light and the flash. The white balance of the flash needs to be a closer match to the ambient light.
The use of remote flashes allows the images to be more dynamic and it also adds a whole new dimension to the final image. Plus didn't have to deal with any redeye in any of the shots which is always a plus. So far the FlexTT5's have worked quite well so will continue to use the same setup in future bouts.
Shooting roller derby is difficult to say the least. The light is always bad and the limits of the camera gear are always being pushed. Simply said it is shooting on the edge of a knife blade. It either works well or it goes horribly wrong. And as it always is when shooting action it is always good to remember "you get what you get".