Recovery..........that's a major point of interest.
As long as I keep my HR at or below 130, it will drop back pretty quickly by backing off a bit.
I mean from 130 to 120 in a minute or 2.
BUT....once I exceed 140, recovery while pedaling is darn near impossible.
And, if i should get things below 130, it takes very little effort and very little time to push it right back up...
Its that old "perceived effort" thing again......

I have yet to be able to push my max above 147, and that was just for an instant. Typically 145 is about as high as it'll go...