Ive used a Smart Carry daily for about five years now. Great holster, and one of my favorites. Its one of the most comfortable and versatile holsters I own.
I think there are a lot of misconceptions about them, and the comments in the negative are from those who have obviously never worn one and dont understand how they work.
They arent a belly band, the gun sits low, below the waistband. When the gun is in it, and its worn properly, it points to the ground (not at body parts) 99% of the time, even when sitting for the most part.
While they are a "deep cover" of sorts, they are not at all slow to access, and even when seated, with "snug" pants and a belt, you can still access the gun one handed. In this respect, they are a lot easier to get to the gun than a gun in a pocket holster in a pocket.
I havent carried my 26 in one "yet", simply because it wont work with my normal work pants. With the right pants, I wouldnt have a problem doing so though. The way the holsters are built, you'd have to seriously and specifically work at getting the trigger to drop in any fashion, even on an unlocked 1911 or a Glock.
I normally use mine as a back up. These days, I usually have my Seecamp in one, but I have used them with a SIG P230, and well as a SIG P239. Most days, I wear "fitted" Carhart type carpenter jeans, which tend to limit the guns size. If you wear something more relaxed or dressy, you can get away with a larger gun.
I make my living "actively" outdoors. I dont lead a sedentary life sitting at a desk. I run around all day, jump in and out of equipment, and climb all over all sorts of things. I have never had the gun come out of the holster, never had it shift position, never had it go off, and as a plus, living in a world of airborne dust and dirt etc, its the cleanest holster Ive ever used. I rarely even see the typical "dust bunnies" I see in my normal IWB holsters, let alone all the other dirt and debris. Its loacation under your pants protects the gun better than anything else Ive used.
A side note on the Glocks and "unprotected" triggers, I would suggest you actually "try it yourself" when it comes to using one without a holster and prove it to yourself, one way or the other. Ive been carrying a second, unloaded Glock around pretty much every minute Im home, for over a year now, sans a holster. Ive been doing it as a test, just to see if it really was the big problem everyone tells you. So far, I have yet to see the trigger drop unless it was done so intentionally ( I use that gun for daily dry fire practice). I even pick the gun up off the workbench/table "by" the trigger, and its still never dropped.
If you are reasonable and realistic in your handling of the gun, I doubt youre going to find its a problem.