Carrying a gun is not the most comfortable thing in the world to do. But if you want to carry IWB than you must get a good quality holster. this is going to detirmin how well the gun feels for you. I personaly use a Galco Sky-ops. I find this holster to be very comfortable. even wheni am sitting down I somtimes forget that I have a G27 on my hip.
Although when sitting it can sometimes take just a little longer to get to your gun. If you practice you can be very quick at it.
Overall just get a good holster and you will find that IWB is not as bad as you think.