Now I'm no flying ace or gunnery expert, but the fact is that convergence is always an issue on aircraft with wing based guns. Setting it to a preset distance is pure player preference. After all you want the bullets to converge at the distance you feel comfortable to shoot at, not shoot at what the convergence is set to.
With convergence the bullet streams are supposed to converge at a given point X yards out ahead of the aeroplane. The bullets fly a cross shaped arc where the mid point is your convergence setting. So if the target is closer or further than the convergence setting there will be a seperation of the streams occuring. However, thats not really a game-breaker (unless you are taking of firing on a target thats waaaaay out of convergence dstance). Remember we are not shooting laser beams from intertially stabilised phaser banks
so you will also have gun dispersion and gravity drop as factors (yes, theres a difference between the allied / german / japanese / russion 20mm variants).
All in all gunnery in aircraft with cernterline guns is a little bit easier.
As for your little tip there, its definitely useful. I seem to do often enough (when upping from a capped field or defending against a picking alt monkey). Its not however that you are flying between the bullet streams (that would more than likely entail a collision on at least one or both ends, since most people's convergence is set to 300-400). The more prominent factors would be gravity drop, gun dispersion and poor aiming. Remember if you have the target in your sights, and you are maneuvering, there's a very poor chance that your bullets will actually hit anything. They will most likely just lag the target and pass on by behind it. You need to lead the target and for long range shots even compensate for gravity drop. During aggressive turn fighting, often enough I end up firing once the target disappears below my nose.
So yes, if you find yourself in a position where you can't evade the shot, point your aircraft to present the smallest profile to the attacker (smaller target = hard to hit), and yank you aircraft to its limits (moving target = harder to hit). Often enough the enemy may not be able to follow your last ditch maneuver and will either break off the attack or miss entirely. Remember though, its only when you've got no other choice.
