Hmm I would categorize his ball busting "hard limit" as more of what I like to call a "soft limit" My preference is that the buttocks are what should hurt the most at the end of the session, not the back, thighs, soles of the feet etc. It is not that those other areas are off limits but rather they should only be secondary targets.

I've stated on more than one occasion that I very rarely do sessions lasting more than two hours.

Might I ask what portion of this session you enjoyed most?