All good points.
I'll give you my philosophy on it which is worth what you paid for it
. Based on personal experience, what I "see", what I read from credible sources and just plain common sense.
All things being equal, more shot and bigger bores(12 versus 20 for example) is always better. Meaning, bigger effective patterns, more room for "error". Recoil and clay target "rules" dictate how much shot to use IMHO...maybe cost now as lead had skyrocketed. Rules meaning FITASC is 1 oz max, International is 7/8 oz, etc. American skeet and trap, sporting still allow 1 1 /8 oz. Sporting in England is 1 oz.
In the old days, 1200 FPS was "heavy" and 1150 was "light". I didn't see much over 1200 until 1oz and 7/8 oz became more prevalent. My understanding of the speed increase was to "improve", widen the pattern with less shot...because you reduce the effective pattern with less shot, 1/8 oz. So, 1200 FPS, IMO, is plenty for shooting any targets. Gains in speed give little in "energy" and none in lead or shooting style. Meaning, do you alter your "leads" if you increase the speed 100 FPS...no...right?
7 1/2's do retain more energy than 8's at longer distance. Less deflected by wind and I've "read" less pellets to break a target. Less...but bigger. Sounds reasonable to me, but we all know shooters that use just 8's.
Recoil is an "issue", both short and long term. It seems to vary by individual, how much shooting, etc. Common sense dictates recoil is not good, so less is better...however anyone works that out.
Just some thoughts.