I've tried them all and never been super happy with any of them. Sitka Bino Bivy (zippers? come on), Marsupial (didn't like the open sides, I kept getting debris in there), Kuiu (didn't like the shoulder strap interface where they terminated on the binos on the old one), Outdoor Vision...
I was a longtime Outdoor Vision user, and it was almost my perfect harness. The features were good, the design is very clean, and the construction and materials are second-to-none (Schoeller Tweave, etc.). I used military equipment made by the same guys in there other ventures and have been friends with them for years.
I had two gripes: The poly stiffener is loud as hell below freezing when you open the flap, and the magnet wasn't strong enough to keep the whole harness from slapping when I'm on my horse.
Sitka was kind enough to give me a Mountain Optics Harness last year, and it's become by go-to. I like the "chest rig" functionality the most. I almost switched to a small military harness I used for parachute stuff in the Army and had a bino pouch made so I could have some modularity, and the Mountain Optics Harness solved that for me. I like the ability to put a rangefinder, calls, chap-stik, wind check, license/tags, GPS, etc. all in the same rig as my binos rather than rig whatever pouches onto a small bino harness or dumping crap into my pockets. I like all of the stuff I constantly access on top of my layers, rather than have to take off or unzip something to get to an item. I'm toying with rigging a holster onto one side for bear country.
This one checks all my blocks. Very happy with it so far after a fair amount of use. Scouting season will fire up here soon as the snow melts and I'll get a lot more miles on it.
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