I am very pleased with MTAC! I carry a Glock 30 in mine. I am right handed and usually situate it on my right hip or a little forward, so it sets under my arm; for me, this also improves the concealment factor.
I've been wearing mine around 4:00, which is comfortable until I have to sit in the car, and then it digs into my kidney. My MTAC also has a tendency to slide around a little bit closer to my wallet, too. I'm pretty sure it's a belt issue, though. I'm planning on picking up a wider belt from The Belt Man before too long to see if that helps any.
The IWB kydex types seem to have a following here. My choice is Raven Concealment. Use it for my Hi-Power on a regular basis. The belt clips on the Raven are adjustable for height so you can decide if higher or lower is better for you. They will custom mold to your weapon at their booth at the Indy 1500. This includes things like adding extensions at the back to shield your bod form the safety and hammer. Very nice people to work with and a great product.
6 foot 260 here and Im in love with Bladetech Ultimate concealment holster, Its IWB and has the inside of the holster coming up far enough to keep my love handle from affecting use. got 1st on ebay and now have one for almost every gun I own.