I generally do not like an IWB holster. It puts a lot of sweat on the gun for one thing and acquiring grip/draw is much harder. But for me, mainly I do not like buying my pants 2" bigger to accommodate the gun. If you don't buy bigger pants it is VERY uncomfortable to wear especially with plastic or kydex that remains very stiff.
When you really think about it, you are still going to put a cover garment of some type over the IWB holster. As such, I just as soon use a OWB loop or paddle type holster that holds tight to the body. Holsters are very particular to body type. What fits tight and prints very little for one guy may not work for another. The larger the FA, the harder it is to hide in an OWB. The advantage of a paddle is that I can take it on and off very easy and it works with my dress clothes...don't need a heavy gun belt. Although the comments about belt are important for an OWB, unless you wear baggy pants the waist generally holds an IWB holster and any belt works. A good belt is critical if you are using a OWB loop type rig.
The best advice I can give you is to go into a gun store and try on several with the gun. There are many factors that go into choosing a holster. You do not clarify your objectives for an IWB, but retention vs no retention is huge. Also, many things to consider in practicing with a holster, especially if it has a retention device.
I have been carrying a concealed gun or two for a living over 25 years and still in search of the "perfect" holster.
I am not quite sure what it looks or feels like, but I guarantee you based upon the boxes full I have, this will not be your last purchase! The life long quest for the "perfect" holster.