This is a great thread. I'm glad you brought it back and that I was able to stumble upon it tonight.
I recently have taken a detour down the S&W 3rd Gen road and could not be happier. My 4566 is the de-cock only spurless hammer variant and is a tack driver (TDM prefix). I never thought I'd ever find another DA/SA .45 that compared to my W. German production Sig P220. I actually shoot the 4566 a bit better than the P220, maybe due to the sights or extra weight, but it is my favorite range toy now. It turned out I liked the 4566 so much I bought a 4013TSW and I like it much better than my M&P40C. Now I just shoot the 40C in 9mm configuration by dropping in an OEM 9mm barrel and leave the .40 ammo for the 4013TSW.