Lynn Nicholson of the circa 1974 Maynard band also uses a low-pressure version of that grip where he only has one finger above the 3rd valve slide and it is obvious that both he and MF are downstream players (as they play higher the trumpet tilts slightly downward).
See the photo at
Lessons with Lynn Nicholson
On the other hand, Doc Severinsen is an upstream player and his grip is just the opposite, so that he only has one finger below the 3rd valve slide:
Doc Frames
A few months ago I discovered by accident that I play slightly better using just one finger above the 3rd valve slide: I am an upstream player.
I just recently discovered that Doc Severinsen is also an upstream player, and until I saw that photo a minute ago I had no idea that Doc uses the same grip that I started using a few months ago.
So the proper grip does indeed seem to help people with their upstream versus downstream playing.
There *might* be a tendency for high-register downstream players to play with fewer fingers above the 3rd valve slide, and a tendency for high-register upstream players to play with more fingers above the 3rd valve slide.
But that is certainly not writen in stone, so every player should experiment with various grips to see which one is best for him.
I have looked in a mirror and I do not see my trumpet tilting at a different angle when I use the 2 different grips, but I do feel the difference in where it causes the pressure to shift on my embouchure.
And although I use the opposite grip style of Lynn Nicholson in his photo (my fingers above, his fingers below), I have tended to adopt the low-pressure end-of-fingers aspect of grip that Lynn uses in that photo in order to force my embouchure to strengthen without using too much pressure, as also Bill Chase recommended in his latter years.
BTW, in his latter years Maynard Ferguson changed his grip from one finger above the 3rd valve slide to all fingers above 3rd valve slide, and a member of his band in the Maynard Ferguson billboard a couple of months ago speculated that it was because of arthritis in Maynard's hand rather than for better playing.
- morris