I carry my G19 in a Blade-Tech IWB with j-hooks. The hooks, as far as I know, aren't meant to make the holster less noticeable, they just allow you to put it on and take it off without having to undo your belt. This is a major advantage for people who have to go into gun-free zones on a regular basis, as I do. I really appreciate this feature.
Depending on the width of your belt loops, the hooks will fit on either side. I wear mine this way. It helps to stabilize the holster as far as rocking back and forth, and it also lends support: since the j-hooks go under the belt, the holster is actually riding on the top of your pants, not the belt.
I'm not sure if BT makes j-hooks to match the various cant options of their holsters. My IWB has an FBI cant, and originally had loops, but I switched them out with the hooks from a straight-drop Steyr holster that my dealer had. It turns out that the forward hook sticks out a bit forward of the holster itself, and pulls my belt away from the waistband of my pants. This isn't really a big deal for me, since I always cover with an generous untucked shirt, at the very least, but if you're restricted in what you can wear, it might be an issue for you.
I have no real experience with the UCH, but I watched a guy at the shop trying to decide if he wanted one. He wore it around the store for about an hour.
It seemed like his shirt didn't want to stay tucked, and re-tucking without exposing his gun was tricky. Might be a dicey thing to pull off in an office enviroment. I don't see how a looped or hooked IWB could have a shirt tucked over it without looking very un-natural. Actually, I don't think it would work at all, but I can't say I've tried it. YMMV
I'm generally pleased with the holster.