I carry a Glock 26 in cargo shorts IWB though with a Glock 19 mag and grip spacer.
I own an XD45 Service model Stainless I can also carry IWB in Cargo shorts.
So, if you are set one one of those 2 and nothing else, I'd go with the XD which is a better choice imho.
Thickness isn't a problem really, I used to worry years ago, but I gained/lost weight, and my guns got bigger.
I wear a long tail T-shirt covered by another short sleeve summer type shirt, like a Guayabera, which I leave unbuttoned.
This isn't me, and the top shirt isn't what I wear, but you get the idea on the ease of concealing with this look/style
http://wardrobeadvice.com/is-it-fashion ... nderneath/" onclick="window.open(this.href);return false;
Is It Fashionable To Wear An Unbuttoned Collared Shirt With A T-Shirt Underneath?
Wearing an unbuttoned collared shirt with a T-shirt underneath is always fashionable. It is a classic look for men of all ages
Big Bang Theory uses the layered look a lot too.