I was applying some pose sets to V4.2 this morning and got to look more closely at what was going on.
I found two things: A) on the individual body parts, some poses apply modifiers (modifier tab). I had to delete several to apply a new pose.
B) on the ball joint constraint, the 3 golden rings should be zero. The pose set puts a value on this and the new pose won't apply right until they are set to zero again.

I am wondering if converting poses to "universal" in P7 would avoid these problems.