I've got three of S&W's "plastic" guns, an SD9VE, SW990L and a Shield. I had the full Apex kit installed on the Shield plus night sights and I challenge anyone to find a better concealed carry 9mm (maybe a bunch just as good, but I doubt better) than the Shield. It's ded-on accurate, comfortable to carry, and more than manageable in terms of recoil or flip.
The 990L shoots just fine with a decent self-defense trigger, good sights, and it's been totally reliable...but then its actually a Walther (they made the frame and all the innards, Smith makes the slide and barrel) and except for the CCP, Walther does pretty good guns.
For the SD9VE I agree the trigger was a bit rough out of the box and rather than shoot half a thousand rounds through it to work it in, I got the Apex spring kit and now the trigger is crisp and light and just right.
My only other plastic pistol is a Walther PPX....with for $279 at CDNN is an amazing buy. One of the best out of the box triggers I've ever had, despite is ungainly looks it fits my hand like a glove, sights are just fine, and on my first trip to the range with it I shot the snot out of the middle of the target. Unfortunately, for future generations, it isn't a big seller (too much competition in the category and it does look bulky) Walther is discontinuing it. Clearly, it ain't a concealed carry choice, but as a range gun or home defense, it can not be beat for the price. We're talking a Walther price like a...a...cheap gun. (Heck, the grips on my Walther P5 cost almost as much as the PPX.)