I don't buy that. I've landed enough perfect hits with the Hurr2D to realize the guns suck even when you have the perfect angle, the perfect spot, you see the fireballs, and you get no result.
My personal experience was that in all my attempts to kill things with the hurr2D, it's far more effective to just take 2 bombs instead. The penetration power is rubbish! Rubbish, I say!!
IL2 guns are far better. The ROF helps, yes, but overall much more effective.