I often have someone who rides along with me when I fly, so we have a lot of experience with the observer/gunner bugs. I will list what i remmeber at the moment.
1. Observer gets credit for a kill
2. Observer can't bail after pilot ejects, has to restart game in fact
3. Observer gets killed
4. When in vehicle with more than one gunnery position, after observer/gunner joins, the host pilot cannot switch positions.
I am not sure how it is supposed to work with the observer/gunner, but if it were me, i would make the observer( for vehicles with zero gunner positions ) a transparent ride-along with no actual stake in the battle, no possibility of scoring or being scored off of.
A gunner however should actually play into scoring , but the fact that noone can switch to any other gunnery positions once a gunner joins seems to defeat the purpose. There should even be a way to switch positions with someone if you are in a vehicle with only two positions, gun and driver(M3, etc.) I understand why if the host/pilot dies the gunner is not allowed to continue the sortie, but even that seems like a possibility if the ability to join that person were removed during the remainder of the sortie.
I think these bugs shouldn't be too hard to quash should they? I hope not, your subscriber base might actually go up if people were able to play together a little easier. (My gf plays often and loves the game, though she doesnt fly she loves to run supps and do supportive type tasks, she also loves to fly as an observer when I fly the single engine planes.)