I also learned to set the flash to high speed sync. I shot most too fast so they came out dark so I lightened them up in ps...
Why would you use the high-speed sync as this will only decrease your flash range (by order of magnitude) - especially on a tele where you need the distance?
Check the flash manual as the high-speed sync do not freeze
the movement and your subjects are all stationary. A slow shutter @ X-sync speed is actually better here to extend your flash range (since you are using a better beamer already)!
-> The faster the shutter speed -> the lower your flash range will be: http://www.photozone.de/3Technology/flashtec5.htm