Bill, the speed I've been using depends on the size and the wood, and what I feel comfortable with. I think it's Bill Grumbine who says if either the lathe or you are shaking, turn down the speed. A good rule of thumb (once a piece is round) is this one, by Dale Nish:
http://www.woodturnerscatalog.com/pdf/safe_lathe_speeds.pdf
I've learned that in a lot of cases, speeding things up smooths the cut, but it usually also increases the chance that a minor mistake will become a major event. Until you feel real comfortable about your tool presentation, I'd stay in the lower rage for safety's sake. All it takes is a small mistake at high speed to become a big problem. Low speeds are more forgiving.
One counterpoint to this is the more voids in the wood, the more high speeds help keep the cut smoother. There are limits, though. Think of a car on a washboarded dirt road. If you go too slow, the bumps beat you and the car to death. Speed up a bit, and you're floating on the tops of the bumps. Up the speed a bit more, and you're sliding sideways on your way to being upside down in the ditch.
Most of my HFs are done between 800 and 1200 RPM, but as I gain experience, I suspect those speeds will increase.