I've got a holster my friend made for me that's basically "Supertuck"-esque. Just a piece of leather backing and a kydex body attached to the front with some rivets. It's extremely comfortable under any kind of clothing. I go as far as wearing it on a belt under basketball shorts and it still stays comfortably hidden. Not sure what the wait is on Cross-Breed and Comp-Tac are but in my opinion these types of holsters are the best for comfort.
The second holster for my G30 that I wear primarily (now that I finally got it) is a Raven Concealment holster. It's not quite as comfortable as the custom "Dan-tuck" as I call it, named after my friend, but it gets the job done well. I like to carry with a light mounted so the all kydex body is naturally wider, but I've been able to also carry under basketball shorts comfortably. The plus is that it can be worn OWB or IWB just by switching belt clips. I've only worn it IWB and have been pretty comfortable with it.
My only gripes with it are that it slides around a little bit under jeans compared to the rough leather backing of my other holster. I think that can be solved with a proper belt, which I haven't gotten yet. The other is that it really can't be adjusted to cant with the standard clips. It's molded with a very slight cant already, but a little more and even the wideness of the G30 plus a light would go away under summer clothes for me. I'm going to be getting some kydex to mess with and will probably make some custom clips myself.
The wait time for Raven Concealment will probably turn you away, it took about 70 days for me to get two holsters from them. Last I heard it was taking even longer than that for later orders.
If you're feeling adventurous, you should try making a custom holster yourself. Molding kydex is fairly simple, and the materials are fairly cheap compared to a complete product sold by Raven/Cross-Breed/Comp-Tac.