I use a Smartcarry front and center at about the 12:30 position. I can carry all day and typically forget I'm carrying. The only issue with this setup, is that it is a PITA to put and take off, and you have an issue when you need to do a #2.
Tried it, didn't like it at all. Can't get to the gun very fast and not at all when seated. What good is a gun that takes 3 minutes and/or undressing to get to? With the proper pants (Wrangler cargo, my favorite), one can draw from a front pocket easy enough even seated and much faster. I bought the "Thunderwear', but same concept as Smart Carry. I tried it, don't even know where I put the thing. Be a good way to carry spare cash on a trip, I suppose, credit card, CCW license, drivers license, give the crook your wallet with 20 bucks in it if you get mugged.
I've found OWB much more comfy. I bought a Don Hume JIT Side for my Taurus 66 3". It is all day comfy, but in coastal south Texas, ain't many days I can use it. I'd rather keep the gun IWB, feel better about concealment even if it's a pain in the side after a few hours. I can do it, just prefer pocket carry. I ignore the gun pocket carry, not a bother at all.
I have an IWB for my revolvers I made that is more comfy than anything I've bought. Weird, eh, but it's a favorite if I want to carry IWB. I have a Sparks Summer Special for my two Ruger P guns and glued a chunk of light leather to it to protect skin from the decocker and hammer. It works as well as any, I guess, for those big, heavy guns.
I have a Mitch Rosen tuckable "Workman" for my Kel Tec P11, but it used to irritate me, too, even wear big puss blisters on my side. So, I started the pocket carry about a dozen years ago and it's been my main carry system since. I've tried it all, nothing beats pocket carry for me in south Texas where it's already over 90 and the weatherman claimed the air was dry the other day....85 percent humidity...
Everyone is different. If you live at altitude in Montana or Fairbanks or something where it never gets over 85 degrees in August and it's 80 below mid winter, hell, you can probably conceal a shotgun most of the year. LOL In Fairbanks, that might be desirable at times considering the wildlife there.
Anyhow, I don't think that if you find IWB uncomfortable, that there is much way to MAKE it comfy for you. I get folks that carry 40+ ounce handguns IWB telling me I'm full of it and I'm going to die in a gun fight because I carry a small 9. BS. I out shoot most of the 1911 shooters I know with my friggin' Kel Tec, not because I'm good, just because they think they don't have to place that big bullet, will kill just from the pressure wave off that big bullet as it passes the BG's ear or something.
I'm as comfy and confident with my 9mm in my pocket as they think they are with their metal brick IWB. What works for them simply doesn't work for me and what works for me doesn't seem to work for them, so we're even.
My advice, experiment. Yeah, you'll wind up with a cardboard box full of leather you don't like, I did, but you'll finally settle on what works for you eventually. Hey, if that's "Smart Carry", then that's what works for YOU. Don't mean I'll like it, but you ain't trying to make ME happy.