My two cents. I set everything as far out as it will go. Since none of my rounds will travel outside the wingspan of the opposing aircraft until they are beyond 1200-1600m, I can hit (allowing for ballistic drop, etc.) an aircraft reasonably consistantly at 600-800 (and have hit at 1.2k), even timing a bandit jinking to avoid my shots. I don't always get a kill, but usually one or two hits will cause him to manuever more, even turn to allow me to close with him. If its a cannon round, then sometimes he's a cripple or kill right then.
Close range with far out convergence is a little disadvantageous, and you get the catastrophic kill less often, but because I'm much closer, I usually can get at least one good hit in without him being in the 'convergent point'. Another turn or pass, and I can often make the kill.
I want to be able to hit my opponent with at least one round at any distance. Even the psychological impact is a big help in winning the fight.
For me, being a fairly good aim at distance, and with deflection snapshots, I think I get my share with convergence set out far.
