Back in '98 they told us at an armorer class that S&W was just wrapping up their exhaustive R&D and finalizing the aluminum-framed .45 compact.
We were told they'd decided to offer a standard model compact and then a more refined compact, and that their marketing studies indicated people (especially cops) wanted something a
lot lighter than the 4516 for a compact.
I ordered my CS45 in mid-'99 when the stainless (slide) version was released. I'd previously handled a friend's early production CS45 in black, as well as his CS9 (also in black), which he'd bought at the same time. Neat little guns, but I'd decided to wait until the stainless models were being shipped.
Then, toward the end of '99 I also ordered and received a 4513TSW, because I didn't want the early carbon steel 457 (and the 457S wasn't yet being offered). Hey, I'm lazy and wanted stainless.
It wasn't until the next year (2000) that I decided to add a .40 compact, but by that time it meant I ended up with the railed 4013TSW.
I was in my early 3rd gen acquisition phase in those years, having started when I ordered a 3913 in '98. I was buying a mix of metal and plastic from 2000 on. I finally ordered a CS9 in '02, and I think the last 3rd gen's I bought were a T&E 4040PD ('06), and then a 3913TSW, as a former duty weapon ('15).
The various T&E and former duty weapon choices I could've bought included the early production 5903/6906's, late production 4003/06TSW's, 4563/66TSW's, 4013TSW, 4513TSW & that 4040PD. I probably ought to have bought the 4563TSW T&W model, but I was more interested in the 4040. I still sometimes kick myself over that one.
I never got interested in ordering any of the larger 3rd gen's, having had my fill of carrying the larger ones as issued weapons since '90. However, another one of my regrets was not ordering a late model 6906 before they suddenly ceased production, dammit. Comes to that, in retrospect I wish I'd not turned up my nose at ordering a 3906 before they went out-of-production.
Oh well.
Now, if only they'd made an all-stainless 3916, or even a 3916TSW, double dammit.