If you are considering any of these pistols, you should also consider the Kahr CM9 (or pricier PM9).
I have a PM9, but I don't IWB it. It's a pocket gun for me. I forget the name of the pocket holster I have for it, but it basically makes the PM9 look like a big wallet in my front pocket.
I like the HK PSK2000 for IWB. It's a .40, but is the best compact IWB pistol I own.