i suggest no mounting for orks at all mounting is for accuracy accuracy is nothing for orks it also has no unfair advantage that it is shouldermount cause every cover you can shoot over is low enough that you always show your upper body half it could be an advantage in some situations (small hills for example) but its still not unfair cause we are aiming for asymetric balance
Orks? Bracing? Nah. If anything, they'd fish out a, uh... Git Finder? Targeting Squig? Dat Squig dem Orkzies use 'fer 'elping dem ta find gits in da battlefeld. Yeah those. And after fishing one out of a pocket they'd put it on top of their head/hat or their gun. And bam, that's how you introduce Squigs to the game.
Bracing?! Wotz da point of good dakka if ya kant stand firm yerself. An' feel da force of da flash pushin yer back on yer 'aunchez!
I don't know how to feel about the camera shake, if Devs add it to Deffguns. I think I would get motion sick from it. We shouldn't go overboard with lore over in-game balance. I think bracing heavybolter, deffgun, heavy shuriken catapult is a nice touch to the game balance; trading mobility and awareness for increased accuracy.