Name something that a 1500 fps .357 load will handle that a 1250 fps load didn't. If you can't, then it's conjecture on your part.

Speaking of 'pre-conceived notions'....one can't maintain 'pre-conceived notions' for over 40 years if they are wrong. You seem to have a pretty good supply of your own pre-conceived notions. You may not be alone, but I don't know many people who will say "hunting experiences are irrelevant" when it comes to assessing cartridge effectiveness. One would be hard-pressed to find a better example of a pre-conceived notion than that.