Using a leaf-shutter setup you can sync at full power at speeds up to 1/1600" provided you're using responsive enough triggers, but the focal plane shutters just don't let it happen for some reason. Even with a leaf shutter, I could never get Elinchroms to sync faster than 1/400" using the Skyport triggers. If you're looking for fast sync with a focal plane shutter, your best bet might be just grabbing some on-camera TTL strobes (580II, 430, etc.) and using the high-speed-sync setting. You'll lose a fair bit of power, but you can always up the ISO and open the aperture a little if you need to freeze motion.