I've heard good things about both those pistols your talking about, I guess It's up to which one feels best in your hands. But as far as using an IWB holster, you'll really need to be willing to spend some money to get as much comfort as you can, not everyone is built the same and the comfort facter varies from person to person. Milt Sparks makes a good quality IWB, and some others have been mentioned.
Savage has a very good point also...I've never found anything as comfy inside my pants as a slab sided single column pistol. Nice and FLAT.
I'm here to tell ya, if you don't have the best quality IWB that fits you right, and is located in the right place, you'll wonder why you ever decided to shove something down your pants in the first place.
I have a friend who carries a Sig and uses a IWB, he likes it, it feels good on him.
Jimster