I've had the Thunderwear holster (Smartcarry's predecessor) for many years and have a few opinions on it's strengths & weaknesses:
Pros:
-It does what it advertises in terms of concealability. *see caveat below*
-You can be flexible in how you use it. I've worn it it in the front crotchal
area, strong-side, sob, and crossdraw, depending on my needs.
-It's a generic size, so you can use with multiple pistols as long as they're of similar size profile. (I wouldn't put a P3AT in a Smartcarry designed for a 1911.)
-Easy on/off.
Cons:
-*Concealability is relative. You'll have a harder time with a 4" revolver than a flat auto. Shorter barrel is better.
-If worn in the front below the belt line, you will have a muzzle in your leg every time you sit down. There's a lot of shifting and repositioning that takes place. Ymmv depending on muzzle length and your particular build.
-Drawing your weapon requires two hands and can be awkward. Driving with your seatbelt on makes accessing your weapon very difficult.
Good luck with your decision.