I bought a better beamer for a trip to the Amazon in Brazil last summer. I was using a 60D, 100-400L, and speedlite EX600-RT. If you are really far away, I wouldn't bother using high speed sync with the better beamer. I'm not sure if one of the links above is to the article that I saw, but you will basically want to set the flashes zoom to a fixed focal length. I think, IIRC, the best spread is had by setting the zoom to 50mm. I think by setting to 24mm, you get a tighter beam, and by going to 80mm a wider beam. There was an article where the guy tried playing with settings and practicing on a wall to see what effect the settings made.
When you've got everything set right, it works really well.
Be careful, if you are walking around when it's sunny and you have your better beamer mounted, you can destroy your flash or camera gear. The better beamer acts like a magnifying glass and will melt right through the flash or whatever gets in it's way if the sun hits it right. I saw some pics last year of melted flashes, some that still worked but were ugly and some that were completely destroyed.