Donnie:
Interesting. Glad to hear that observation.
I think that kind of realization is very exciting and managed well it can stay that way. Only downside is so many problems can occur so quickly just over that exciting speed differential that can make a course's greens as fun and interesting as you just observed and experienced. The problems just over that differential are both with playabliity as well as course maintenance (both set-up and agronomically).
To me this is a large part of the ideal maintenance meld---eg finding that PARTICULAR speed differential for your PARTICULAR course. And obviously that is going to be different from course to course for a lot of obvious reasons (that so ironically have never before been all that obvious for some set of odd reasons
).
It's looking to me suspiciously like an almost ideal speed differential may be around 9.5 to 10.5.
The reason I mention that speed differential is many-fold. Firstly, in play, 9.5 to 10.5 is a whole lot faster than most all golfers think it is. If you ran an actual 10.5 most all your golfers would think it was 12 or 13.
In my mind, and from about three years now of actually experimenting with this on a whole slew of golf courses, once you get into that 9.5 to 10.5, as you just observed, raw physics takes over and an exponential effect on ball roll takes over big-time. That creates an effect where the architecture (slope and contour of even the imperceptible and nuancy kind) just begins to really pop. Some of us call that "turning the lights up".
With a speed differential of about 9.5 to 10.5 the lights go up bigtime on maybe 1% to 3% grades. Grades higher than that can get a bit problematic though since once a ball reaches them down grade it builds up too much speed to stay in areas golfers want it to eventually.
In my opinion, once speeds get over an actual 11 playability even on 2% or 3% can get sort of crazy. The effect in play is what I call "ball creep" and it is just amazing over 11 even on those grades. The reason "ball creep" kicks in so dramatically at that speed is, in my opinion, that's the point where lack of friction kicks in bigtime.
But it is amazing how this differential that may be around 9.5 to 10.5 greens can go so quickly from mundane to super exciting to crazy. With the light analogy it's that they go from sort of dark (around 9) to highlight (around 9.5 to 10.5) to way too blinding (just over 11).
It's sort of too bad those parameters are so narrow but they are. It's physics in the end and we sure can't change that.