Here is MY devalued-2-cents of the American dollar:
IWB is something for people who prefer to do it to conceal the gun barrel length, while covering the handle and such with a short-waisted jacket, vest, or other outer garment.
OWB with a pelvis-curved pancake style holster is my final resting spot on comfort and carry.
The new Galco Concealable, and newer versions of the Fletch Glaco copy some custom makers' design of the flat, curved side to the body, and the contoured, molded shape of the gun on the outside. I love this style for pure support, balamce, comfort. The FBI forward cant really balances the gun weight, and my bending and stooping motions.
I have a bin full of IWB holsters, and I have not gone back to them. Same with the shoulder rigs, Small of Back, Cross Draw, thigh rigs, paddles, clips-ons, roto-tilt, etc.
By the way, I use the new contour Fletch to carry a Bobtail 1911 everyday, comfortably. I have even done the same with a more bulky gun, such as the HK USP45.
The only guns which barely worked IWB for me, are the slim slides like the 1911, Kahr, and similar thickness guns. The thin but stiff materials like bullhide and Kydex worked best for me.