The 3913, and all of its model variations, is one of the most under-valued 9mm pistols on the market. It's probably the BEST 9mm S&W has ever produced ...
The TSW versions do offer some interesting "advantages", if you will ... no matter if you chose an early "pre-railed" model with the shortened grip frame, or one of the newest TSW's with the standard grip frame and the rail.
The value of the "accessory rail" notwithstanding ... most folks either like it, or don't ...
The TSW offers "Box Type" frame rails, which do offer some advantages in potential accuracy regarding slide & frame fit, but still offers the reliability for which the late model S&W pistols are noted. These are larger dimensioned frame & slide rails, and also extend to the "rails" in the dustcover.
The visual chamber inspection port (in the rear of the barrel tab) is a handy thing to have ... I use mine on my 4013TSW more than I'd expected.
The TSW model barrels were originally slightly modified to allow for slightly delayed unlocking, which can offer some lessened perceived recoil. Not a big deal with the 9mm for many shooters ... and I haven't asked to see if the later production standard model variations (908/908S) have received the same treatment by this time.
The current production TSW slides, last time I checked, were pre-milled and drilled to accept the optional Spring-Loaded Decock-Only assembly, instead of the standard Manual safety/Decocker assembly. This option requires a factory techician or armorer to install it, as the sear release lever must be checked against the new part for tolerance in decocking "timing". The sear release lever may have to be replaced to accomodate the new decocking assembly, and the sear release lever is one of the few parts that still requires "fitting" in most pistols.
I have a friend who owns an early 3913TSW. He likes it a lot. He's exceeded 10K rounds through it, and his pistol has given him perfect functional reliability, even though he doesn't clean it as often as he SHOULD.
He claims it gives him a reason to visit and have me inspect the pistol every few months.
This is the same guy in whose SW99 pistol frame I once discovered SAWDUST when I inspected it. (Not in the bore, by the way). He gave me one of those, "Oh yeah ...", and proceeded to explain how he'd been doing some fence building on some property and hadn't yet gotten around to cleaning his pistol. His, "What's wrong? It's still working fine ..." reasoning is always good for a butt chewing from me, but I think that's one of the reasons he enjoys visiting.
I know another guy who owns a 3913 from the very early days of production, and who'd quit counting the rounds he'd fired through it over the years for training and competition, although he said he knew he'd fired more than 10K rounds, and that was a few years ago ... and his pistol required some new parts due to wear, and some new magazine springs. I ordered approx $100 in parts (my cost) and he was back in business ...
I don't shoot my 3913 as much as either of my friends. I only have somewhere between 5-7K through mine, I think ... but that's because I own and shoot quite a few pistols for work, and the majority of my 9mm gets fired through my issued 6906 ... approx 30K+ and counting (although I've replaced some parts as preventive maintenance, and finally chipped an extractor and broke a trigger play spring at one point).
If you go over to the S&W forum, you can find some more owner experiences, in addition to folk's opinions to be found here ...
http://www.smith-wessonforum.com/cgi-bin/sandwcgi/Ultimate.cgi?action=intro&BypassCookie=true
Go to the Semiauto Pistols section ...
It would be a hard choice to decide between one of the new 908S models, and a new 3913TSW. If I was buying another one, and I had the money for the TSW, that's what I'd buy. But, there's nothing "wrong" with owning a 3913/3914/908/908S, either ...
I'd like to add a new 3913TSW, or maybe even a 908S, to my safe someday. Compared to my late production 3913, the newer production methods are producing some very nicely machined and finished pistols. They've made a great pistol model even better ...
Of course, I'm biased toward them. I think the 3913 platform, in all its models, is probably pretty much state-of-the-art when it comes to a metal-framed, TDA, single-column magazine, reasonably compact 9mm defensive weapon. It balances well, fits a broad spectrum of people's hands, and offers a reasonable balance between compactness and "effective" caliber. About the only "improvements" I think merit some consideration are night sights and Hogue grips.
Not a bad pistol ...