why would one choose the Osti over the Wirb...the Wirb has better visibility in the gunsight making it easier to track crossing targets. Lethality wise they are extremely close within 1.5k. because the Osti has poor barrel stability it offers little benefit in killing fighters that are diving on you and Bombers absorb the 37mm like its made of memory foam.
If something is within 3K and flying head on, it's in serious danger. If it's anywhere within 1.5k, it's not going to make it over your head.
One shot on a fighter, a bare handful on bombers, more effective against light armor (can even kill Panzers last I checked it), and the sheer intimidation factor of 37mm shells zipping by at 3k out.
I find it much more effective at maintaining some breathing space, since nobody even kinda slow wants to get close, and nobody wants to fly head on. Even if it's not as effective at knocking down a lot of aircraft if they decide to swarm you anyway.