I like Sidearmor kydex IWB holsters for the occasions that I carry my Glocks IWB.
FWIW, though, I usually prefer a paddle holster instead of IWB as paddle holster carry is more comfortable for my fat a$$.
I just got a G-Code kydex paddle for my G22/31 and one for my G19/32/23 and will soon get one for my G30 and maybe G21. I love the design of the G-Code. It has the best paddle design I've seen on a Kydex holster and the fit of the holster is great. Blows my Fobus out of the competition! If you're interested in a paddle holster I'd recommend checking out G-Code. Ther website is here:
http://www.tacticalholsters.com/gcode.htm
I checked them out mainly because Sidearmor didn't offer a paddle unit but I now think that G-Code paddle design would be hard for even Sidearmor to beat. It's the most stable paddle holster I've tried and it really holds close to my body, unlike other paddles I've tried.
As for belt slide holsters for OWB carry, I love the Kramer horsehide belt slide that I have for my CZ 75B and like a couple of the Safariland models for my Glocks. I don't carry OWB belt slide often enough to invest heavily in this type holster though, so I'm sure that someone else could be of more help in this category than I am. Usually, if I'm not wearing a paddle holster or carrying a Sidearmor IWB, I'm carrying a full tilt Accumold duty rig from Bianchi. I somehow doubt you're looking for that type carry rig though.
By the way, Federal Hydrashok 230gr is a great load for the G30. Shoots great in mine, anyway.