I've experienced excellent service from my late production 3913. Outstanding example of everything a compact, lightweight, single column, metal-framed, TDA 9mm defensive pistol ought to be in the opinion of many folks. I'm one of them.
Now, if I were to buy another one I'd pay the extra money to pick up a 3193TSW. Why?
Well, I happen to think the larger, wider frame & slide rails of the TSW model might offer a bit more inherent potential accuracy.
I like the visual chamber inspection hole in the TSW's barrel tab. Makes it easy to see a case rim in normal light. Been handy on the firing line.
S&W claims the TSW models benefit from delayed unlocking, and therefore slightly reduced felt recoil. I can say that the 3913TSW's which I've handled and shot have seemed just a bit easier handling at times during shooting. Might be something to it.
The current TSW slides receive some additional machining so they can accept the optional spring-loaded, decock-only assembly, should an owner/user want to have it installed at some point.
While I haven't had a problem with the magazine catches on my CS45 & CS9, being part of the previous Value Line series (now the American Pride series) they use the plastic/metal magazine catch assembly, instead of the metal one used in the TSW (and previous standard 3rd gen) series. The metal one is adjustable, meaning the engagement of the magazine catch with the magazine's catch notch can be adjusted.
There are some other cosmetic and minor parts differences.
The 3913TSW is more expensive, but I happen to feel it offers just enough minor improvements to make it worthwhile over the long term. As far as just an 'issue' defensive pistol, though? I'd have no problem carrying or using a 908S as an everyday off-duty weapon, or issuing them to anyone else.
I carried a couple of different 6906 pistols as issued weapons for several years and have a lot of confidence and faith in them if they've been properly maintained (as with any firearm).
While I have recommended a 3913, and then the later 3913TSW & 908S models, to various folks who favor TDA pistols, I've also recommended the CS9. I think it happens to be a very under-appreciated subcompact 9mm TDA pistol.
I actually choose to carry my CS9 much more often than my 3913 nowadays. Matter of fact, while my 3913 still sees a reasonable amount of range time, it otherwise remains in my safe, having been replaced with my CS9, G26 or one or another Airweight J-frame for off-duty usage.
Between the 3913TSW, 908S, CS9, SW990L ... and now the new M&P 9 Compact ... I think S&W has created an outstanding selection from which to choose a compact & subcompact 9mm pistol, whether someone's prefer be polymer-framed DAO-type or metal-framed TDA type models.
One thing I'd like to see changed is for S&W to produce the SW99 in TDA again for the commercial catalog, instead of just offering it to LE/Govt purchasers.
Well, I'd really like to see the 3913TSW produced with a Scandium frame, too. Just because.
Okay, and I'd also like to see the release of a new 6906, probably called a 6913M, with a Scandium frame and a stainless Melonite treated slide.
Nobody asks me about these things, though ...