Btw, I find the 109E cannons to be far easier to hit with than, say, the 30mm Mk 108 of the 109K. Just set them to 200 yards and get close. They're more effective when the target is in a slight turn; from straight 6 o'clock it can be a pain.
Well of course they're easier to hit with, they're 20mm's after all, but I wouldn't call them
far easier to hit with. In any case whatever advantage in ease of aiming the MG/FF has over the Mk108 does not go far enough to actually make up for the fact that it doesn't do much when it actually does hit.
As far as synchronization, I do not think they're synchronized, as they clearly fire outside of the propeller arc, rather that it's just the poor design of the cannon that causes it to have a slow rate of fire.