My thoughts...
I probably wouldn’t spend money on a letter as I doubt that Roy has any enlightening information to share, even though I would love to read whatever he might say. I’ll also say that either the fantastic photos mask any condition dings or blips -OR- man, that sucker is in high grade condition, it just looks plain mint.

Oh yes... the thumb safety! The left side picture confirms what I suspected, it simply looks like a production single-sided safety put in there, not what most PPC-9 pistols shipped with. Typically you would have a single sided flat black hammer block with a longer extended and enlarged paddle. It actually looks very much like the hammer block thumb safety that was OEM on the Model 745. The 952, 3566 Limited, 845 Limited and 4006 Limited all wear the same hammer block thumb safety that (I believe) your PPC-9 should have shipped with too.

Not a big deal, but to hard core PC enthusiasts, it does stand out in the picture! On the range, it means pretty much nothing, I’d think. And of course, extremely easy to swap the part in/out but I would guess that the “correct” part would be quite difficult to source.

I’ll also say that $2,100 in cash would be under market for a PPC-9 in that stunning condition. She is a beauty!