I received an email from CCI with the same info. I never got a clear answer on any other brand, but I swap CCI SPM and SR without worry. I usually find the SPM cheaper, and more available so I use those.
I heard the same thing with 327 federal about using small rifle primers, and that can run up to 45k psi. I've used all primers successfully, and choose the one that is most accurate or consistent with that particular load. Another note about CCI primers, the small pistol cup thickness is EXACTLY THE SAME is the small pistol magnum. The only powders I've found so far that work better with the magnums in 327 federal is AA #9 and H110. Every other powder I have much better results with standard primers. The Federal small pistol primers are very thin, and do get nice and flat with max loads, but I've never had one pierce or leak.