Your test results are very interesting. For basic target use, I primarily load Dardas 158LSWC-BB, for .38spl / .357 S&W revolvers, & 200LSWC-BB, for .45acp Colt 1911's.
Generally speaking, I use magnum brass in the .357 revolvers - even for light, paper punching loads.
I notice that you don't make much reference to accuracy, in your posted results. Most would "expect" that the low SD / ES loads, would provide the most consistent accuracy results, but what have been your findings - in that regard?
Also, if I'm not getting too far off track, have you tried different diameter expander dies - for your 12BHN cast bullets?
I've been using the Lyman M (for ease of bullet seating), & as I got two in 38 / 357, have considered turning one down a few thousandths. Thinking a slightly tighter grip, might improve the burn consistency - for light target level, CB loads.
Just curious.