I've used a couple of Smart Carry holsters daily for a couple of years now, and have been very happy with them.
A lot is going to depend on what type pants you wear and the size of the gun you carry. I wear Carhartt type pants, which are "flat" across the front and while somewhat loose, they are not very giving. I usually carry a Seecamp when I wear them. If you wear something like a pair of loose fitting, pleated Dockers, you can get away with a bigger gun with no troubles. I've used a SIG P230, P6, or P239 with pants like Dockers or sweat pants with no problems, but thats about as big as I'm comfortable with.
The Smart Carry holsters are well made and basically water/sweat proof (especially from the side facing you). They are comfortable and work as advertised. I work physically outside year round, in pretty nasty conditions, and the Smart Carry offers the best protection of any holster I've ever used, especially when it comes to dirt and dust. My Seecamp has virtually no crap in or on it, unlike the P229 in my IWB holster. Even when I'm soaking wet with sweat, including the front of my pants from it dripping off my tee shirt, the gun is still dry at the end of the day.
The only issue I have with mine is, the gun will eventually start to wear a hole in your pants at the rub point(s), and I have to use a piece of "iron on" patch on the inside of my pants at this point to stop/slow it, otherwise, I get holes worn through the material. This is more of an issue with fitted or snug pants, and less if any issue with the loose fitting pants.