This is strictly my opinion, but it's not the comfort that would concern me, it's the access - seems like an awkward "reach" for drawing the knife AND resheathing it.
Unless you're blessed with freakishly long arms? lol
Funny story (only because it didn't happen to me): when I was a kid, most of my camping gear was old Army surplus equipment - including oldschool "ALICE" webgear. My running buddy and I carried our knives upside down, attached to the shoulder strap - mine an old Gerber, his one of those Buckmaster "Rambo-style" knives. Anyhow, one day we were sprinting across an open field when his knife was jostled out of its sheath, where it landed between his feet. Don't know if it sliced him on its way down, or if his leg came down on the blade of the knife while running full-stride, but the result was about two dozen stitches if I remember correctly. I bound his sliced-up calf with a couple of bandanas and fireman-carried him back to the house so his parents could drive him to the hospital. Maybe it's that dark, repressed memory that makes me leery of this post? lol
KD