I'm a quiet Bish that loves this game--I mostly GV but now and again do the Spit thing. I have to weigh in on the issue of gun shake.
I personally have fired coax 7.62mm on a variety of armored vehicles, pintle-mounted .50s and 7.62s, and a 20mm gatling gun firing 3000 rounds per minute on a M113 chassis (Vulcan).
For the coax guns, there is no shake. Zero, nada, none, not one iota. Ok, there was once but that was because the idiot loader didn't connect the front pin. As the tank commander, you can't even hear the thing firing while wearing a CVC (helmet with earphones).
For pintle-mounts, 7.62s rattle your teeth but don't shake off target or your view (unless the sound makes you blink and flinch) if you lean in to them. A .50 on a pintle will dance a bit if you fire sustained bursts.
While I've never fired an Osti, the Gatling on the Vulcan, which is a hydraulic mount like the Osti, had zero shake when it fired. No wandering sights, no vehicle shake. That's logical when the cannon is hard-connected to the entire vehicle; the vehicle itself is a recoil damper. I just don't see how it's possible that the small cannon on the Osti shakes the whole contraption like it was a ground mount poorly set.
Especially with the Osti, I have seen a marked effect on accuracy with the update. I'm not talking about a 400 mph cross-shot on a vulching LA7, but rather a big as a billboard mosquito doing a straight strafing run into my gun. With the update, in my view, the LA7 will live where before there was at least some chance I could tag it. The mosquito driver now might live, where before there was no chance. The head shake is more like a handicap. Worse, it rewards poor flyers.
I know there are a lot of views on the issue and AH. Reality, gameplay, whatever. In my view, AH is an admirable balance among all factors. Particularly with the Osti, however, in my opinion that balance has been shifted away from both fun and realism with the gun shake update.