I carry a 4" XD 45, IWB. I've got the compact, but I've decided I prefer to carry with the full size mag. It's summertime now, so I'm only covering it with an untucked polo shirt. It definitely prints. You won't miss it if you're looking for it.
But nobody is looking for it. People don't pay attention to that sort of thing. So no one has noticed it, afaik. I could conceal it better with looser shirts... not that I really care either way.
In the winter months when I'm wearing a couple more layers, it conceals just fine on my 6'2", 230lbs frame.