You don't feel it would be too chunky/fat to conceal without printing for a relatively skinny person like myself (5'7/140lbs/30 in waist), or no? I plan to wear a slightly loose fit t-shirt, but nothing ridiculously loose or baggy, ya know? Think I could pull it off at my size with good belt and holster?
Im 5-6, 155# with a 32-34" waist depending on the pants, and carry a Glock 17 AIWB daily, including under just a normal sized tee shirt in the summer. I carry my 26 in a Smart Carry as a back up on occasion, or on those rare occasions I cant carry the 17. Printing really isn't an issue, unless you're doing something really weird, even with the 17.
Ive handled a couple of 365's but haven't shot one. Just didn't see that it would do anything better than my 26's and I lose the commonality.
The 26 is a great gun and shoots and handles like a full size gun, at basically the same distances, and with a simple mag swap, basically is one. It will take any of the larger 9mm mags without issue.
It will also use, or can use, the same holsters as the full size guns. Which can be a plus when carried AIWB, due to the short barrel and top heavy weight.
Depending on the holster and how it attaches to the belt, the longer holster can stabilize things better and help with keeping the gun from flipping out if you bend over. A good kydex holster with proper clips pretty much eliminates this though.