Bernd
Your continued work is I am sure extremely well regarded and much appreciated. It is very heartening to see esteemed members and indeed a broad spectrum of the PPRuNE community responding to excellent chairmanship, summation and guidance from PBL and yourself.
One point about hydroplaning/aquaplaning, if I may - I am not up with the discussion enough to understand the full significance of it now, but I hesitate to accept that the "function of the square of tyre pressure only" theory was as well known/accepted in practice as it has become with recent hindsight.
I learned the 9 x version in ATPL theory I think, but it wasn't dwelled upon in class or study notes. You really have to be a good physicist to fully understand why it is so I think. So, at least in ATPL theory, this 'phenomena' was almost treated as just one of those interesting things worth an extra mark or two. The only consequence of failing to 'know' was the loss of a mark or two. As a piece of theory, it certainly didn't receive the same attention as the speed of sound being a function of temperature only, for example.
As I said, I am however no expert, so I don't know if type-rated pilots are expected to be much more aware of consequences of the theory than I was.
So I wonder if it might still be fair to say that any hesitation in braking was a natural reaction to the knowledge couplet of a reported slippery runway and any 'feeling' after touchdown that indeed it was so.
Certainly until reading the thread, and despite being taught enough about the tyre pressure angle to answer a simple exam question correctly, I would have been one who was tempted to stay off the brakes at higher speeds in the (false) assumption that I was improving my chances of a controlled stop by allowing the one reverser to do the lion's share of the initial deceleration work first. It's moot if the brakes aren't effective anyway of course, but might explain any hesitation.
My apologies if this is too simplistic to be useful.