I don't think it's one or the other ("taking ukemi" or "being thrown"). There is a continuum that ranges all the way from letting a 5-year-old execute kokyunage on you, to finding yourself on the mat and not even knowing how you got there. The latter has never happened to me, but I've felt quite a bit of the scale over the years.

I could see how the possibilities of experiencing the higher end of the scale would diminish (potentially to zero) as one's own abilities (or whatever ) increase relative to those of the people with whom one is training. Under this conception, O-Sensei might experience everyone the same way I experience training with my kids' class.

I think this is the point Chris and Dan are trying to make. It makes sense to me.

Conrad