As explained in the previous thread, I don't think there is significant difference between high speed or low speed Mach buffet. Perhaps the frequency changes gradually with Mach number, and that may be noticeable if there is a large spread between the high and the low limit. But since an airline pilot never gets there, would he be able to recognize the difference?
Having experienced both as FE on test/acceptance flights on the Nimrod and L1011 I can say from my experience the buffet itself wasn't much different and had we not been aware of which regime we were entering I'm sure we wouldn't have been able to tell from the buffet alone.
I imagine that AF447, by the time it was at 380 with TOGA and 16° alpha was getting a bit of both!