Cajun called again today. Three different people went through my two P09 and one P07 pistols, post installation of the Pro kits, and none of them could make the trigger malfunction. They asked me to take them, try to make the problem happen, and in the mean time send back my three problem P09 pistols.
That lifter part is quite early in development, and not something that I see as a short term fix.
We also discussed this issue generally, and they said about one in ten stock guns coming in, exhibit the problem.