HSTA is definitely tougher than HSCh - the cardio is tougher (and longer), and the weight segements are more challenging. HSCh is fun, don't get me wrong, but HSTA seems more advanced. HSTA has some interesting moves like one-armed tricep dips, push-ups traveling over the high step, and one-armed lat raises while resting on the high step. HSTA is more of a straighforward circuit workout: cardio/legs/tris-cardio/legs/shoulders, etc.; whereas HSCh is almost like a bootcamp workout in that you do a move for about a minute and the tricep work, for instance, isn't grouped together. I hope that made sense.
By the way - I do High Step Circuit on a 8" step during the cardio segments (as soon as the cardio segments are over I hit the 'back' button on my DVD so that I do each cardio section twice). During the lower body moves, I typically set the high step at 14" and I hold a dumbbell or Body Bar during all of the lower body moves. I use heavier weights for upper body and high-tension tubing. Also, I do most of the ab work on the floor as opposed to on the high step. I feel like I get a great little workout in under an hour.
