There is 45 colt cases with small primer pockets? I must be living under my rock again....
But yes, back off about .1 grains of your regular load in standard pistol loads is the consensus on using SPMs in place of SPPs.
Revolvers have a nice amount of firing pin inertia to indent the slightly thicker primer cup metal. Now in striker fired autos is where I might have a slight concern, but again that would probably still be fine, although I've never had to try it.......not yet anyways.
I would not use lesser primers in bigger cartridges......like SPPs in place of SRPs is a no-no. I also don't want to use only SPPs in place of SPMs with something like H-110 or W-296 either.
I'm thinking you can use CCI SPMs in place of SRPs. I've read they are the exact same thing, or close enough to not have a difference. But again if this were true, then why wouldn't the company just indicate that to us consumers making their product more versatile and simplify the whole process? WW sells them separately and since WW has LPP and LPM in the same product, then their SPMs and SRPs are probably different.
If you experiment outside of published data, always start at the LIGHTEST published starting charge you can find out there.