I'm watching that thread rather closely
usually I'm the one doing crazy conversions (Marlin rifles),
but with S&W, since I just recently got into them,
I've got a ways to go in the learning curve!
Guys do it with the cs40 and the cs45. Since it's the same frame for either, I don't see why you wouldn't do the 40 since all it would need is a rechamber and a recoil assembly(well, and mags, unless you wanna go the 1066 mag route).
I really, really like the smith tda alloy pistols. The single stacks really shine IMO. If I were you, I'd find a 4040pd and convert the cs40(if, you know, you have too much money).
I wonder, if a 3913 slide could fit on a 4040d frame.....(and by extension, a 69xx slide, or in fact a 59xxslide). Then one would have 9,40,45,10mm all in a similar size pistol with identical controls and layout. Someone get a 4040pd, and we can play Legos.