As for drop safe, at half cock, you would have to jar the hammer off the notch AND then break the FP block to get a discharge. Nothing is 100% but 2 safety features working in series is better than 1 or none.
If safety redundancy is important, you might consider a Tanfoglio version of the CZ pattern, which also has a hammer safety giving you 3 safety features! I think you've changed your argument a bit, and maybe now understand how the CZ firing pin block mechanism works.
That said, I will continue to argue that there's no reason to believe that the safety notch on the hammer has any meaningful role to play in drop or external-blow safety -- it wasn't designed for that role and none of the gun makers using that feature ever advance that as a (drop/blow) safety feature.
I'm a fan of the decocker models and I never lower the hammer beyond where the decocker stops it for the reasons stated, plus the fact that the DA is better from decock/half cock/safety notch than it is from the dry fired position.
I only own ONE decocker-equipped gun (a Sphinx SDP), but have owned a bunch of SIGs over time. I have never experienced (nor observed) a problem when manually decocking a gun. My reason for starting from the half-cock notch would be because that's the only practical way my decocker-fired (which is a variant of the CZ pattern) gun works -- so doing so has nothing to do with concern about the firing pin block failing.
I'm very comfortable manually decocking a DA/SA gun and I just don't like different first and second trigger pulls. I feel that cocked & locked start is far better than starting from the decocked half-cock safety notch on a CZ. A lot of DA/SA guns don't start from a hammer's safety notch, but all of them have different first and second trigger pulls. Nearly all of them have firing pin safeties.
As I've noted before, everybody says that the issue of the different first and second trigger pulls with DA/SA guns can easily be mastered with a bit of practice. I know that it can be mastered, but I don't think it's an easy or quick mastery. I also suspect that far fewer shooters master the DA/SA transition than they claim.
Back when I was very active in IDPA, I was the one who designed our local IDPA match courses of fire and also helped (as a SAFETY OFFICER) with scoring. Small 2 shot groups on first strings were not something I saw a lot. It's not something I see a lot at the indoor range where I shoot most often. When I was shooting my CZs or a Browning Hi-Power in an IDPA match, I just chose to shoot "Enhanced Service Pistol" which let me start from cocked & locked. Most of the time, that's how I now carry (when I'm not carrying a striker-fired gun); truth be known, however, I now own, use, and carry more striker-fired guns than hammer-fired guns.
I think its far easier to master safe manual decocking than mastering the DA/SA transition.