*shrug* I've always been told that O'sensei' stuff hurt, Tohie's stuff hurt. I don't disagree with any of the other stuff regarding center, but the notion that there should be no pain or that if it hurts it's wrong seems absurd to me.
None of this has anything to do with "relying on pain" btw...
The notion that pain is acceptable, "relying on it" or not, in Aikido, is absurd to me. The way to practice Aikido in said manner is available for those who want it. We all make our own choices.