gaijin,
I dont have the dvds and I am not a fan of this genre, but I recollect VF opinions when these were released. iBallet has quite a following there. The consensus comparing iBallet to ATRM dvds seems to have been:
- Grace is an excellent audio coach but her form on video isnt the best
- The audio iballets are more intense and varied
Personally, I enjoy Garce's itreads including the itread ballet (alternates running on the treadmill with ballet moves where you use the treadmil handrail as the barre) and the workouts where she co-taught with Keith.