This is in part dependent on specifically how the pistol in question is tuned. The main issues that i can think of are light strikes/over penetration and Short Reset parts compatibility.
Much like the CZ 75 variants, when reducing the Hammer Spring weight in the CZ P Series a reduced power Firing Pin Spring and an Extended Firing Pin are used in some cases to maintain consistent primer ignition. Primer hardness figures into this equation as well.
If a given P series lower/frame with a lightened Hammer Spring is matched up with a Factory stock slide you may encounter light strikes. If a P Series slide with an Extended FP and reduced power FP spring is matched up with a factory stock P Series lower/frame one might encounter over penetration of a primer. I have not encountered this my self but i assume that it can happen with the correct mix of parts, spring, and primers. Avoiding the effects of mismatches should be easily achieved with a few parts changed out or a hammer spring weight adjustment.
The CGW Short Rest Kit (part of the Pro Package) may also cause compatibility issues. Obtaining a short reset requires a modified low lift Firing Pin located in the slide and a modified FPB lifter arm located in the frame. These two parts work together to reduce the reset distance and make up the CGW Short Reset System. Along with the CZ75 variants, in the P series a slide with a low lift FP can be used on a frame/lower without a SRS FPB Lifter Arm. In contrast, a slide with a factory FP would not work on a frame with a SRS FPB Lifter Arm. This is because the SRS Lifter arm would not raise the FPB plunger in the slide high enough to clear the notch in the factory Firing Pin.
An interesting subject, i look forward to hearing other forum members input on the topic.
