I'd be curious what actual fire results would look like. It's not that I don't value LaserLyte type products, but I'd put more faith in results with live ammunition (though I suppose LaserLyte is sort of the ideal case, I just find under live fire more human components of shooting come into play and can make differences in technique/mechanics shrink somewhat).
My guess is that live fire results would have an even greater discrepancy, but I feel no need to test that hypothesis.
My other comment would be if you were trying to compare to DA/SA firing, it shouldn't be all DA or all SA. You should have a group of all SA and then a group of one DA and the rest SA. I get what you're saying about your DA precision vs. SA precision, but DA/SA is a mix of both with the large majority SA. I have no doubt that the one DA and then the rest SA group will likely be larger, but I don't think the group size would be twice that of the all SA group. For those that haven't done much practice with DA though it's certainly possible for it to really throw a wrench in the works. It's a system that requires a lot of practice and few people devote the time. Frankly I think there are easier systems to learn that are just as safe and I'd also accept that argument that first shot accuracy can be critical.
You are right, the precision of a string of 15 shots, for example, with the first being DA and the remainder SA, would have a precision greater than a SA-only string, but nowhere near as large as a DA-only string. It is a simple matter of simulating the results using DA-only and SA-only precisions and combining them in whatever length string of shots you desire. By the way, when being lazy while dry firing, it is easy to forego cocking the hammer each time, thus generating a lot of DA-only data.
Many argue that practice will get rid of the precision discrepancy between DA and SA modes. I sincerely doubt it. Assume, for example, that the circular error probability for DA at a given distance is 2 inches, and only 1 inch for SA. By practicing I can see how one might be able to reduce the DA CEP to 1 inch, but the acquired skill will certainly result in the SA CEP also being reduced. Mechanically, the longer and heavier DA pull allows more opportunity to deviate the muzzle's alignment with the target.
I can send my 75 Compact off to Cajun Gun Works and get the DA trigger pull tuned, decreasing it from maybe 12 pounds to 6 pounds, and get the length of the DA trigger pull reduced. This would certainly improve DA precision. But, while I'm having them tune the DA trigger, I'm going to have them tune the SA trigger, too -- lightening it from maybe 6 pounds to 3.5 pounds. Thus, mechanically the SA trigger will remain superior.
I omitted the first-shot accuracy importance argument, as it seems obvious. The first shot is presumably the most important shot in a DGU. I like to say I can't afford a DA warning shot, nor do I require a DA fouling shot.
I really don't care whether or not someone carries DA/SA, SA-only, safe-action, condition 3, or if he/she doesn't carry at all, nor as I said do I want to get into a debate about DA/SA versus SA with safety as we have plenty of threads on here about that. It's a fair discussion to get into given the OP's question, but my comment was strictly about what is "safer" when decocking. I prefer to take as much of the human out of the loop as possible and if the desire is to carry in a DA/SA mode I would rather the dedicated decocker. My assumption is the OP hasn't decided what mode of carry he/she prefers, and that really would determine what part I would install personally. And I think for the third time I've said this on this thread, this isn't a case where you have to make a permanent choice. The P-09 allows the owner to see what works best for him/her with the option of swapping parts. The simple answer is for the OP to just try for himself/herself.
We are in violent agreement about a decocker being safer than manually decocking, although I do agree with Walt that manually decocking to the half cock on a CZ is awfully easy to do safely.
Even though I have never carried in Condition 2, I practiced decocking my 83 and 75 Compact until I could do so confidently with a loaded chamber in my home. It helps to examine and understand all the safety features on a gun. For example, the 83 doesn't have a half cock position or a firing pin block, but it has a rebounding hammer safety. By releasing the trigger right after the hammer is released, there is no way for the hammer to strike the firing pin, even if it slips.
