This thread was an interesting read. As a pilot/captain, a few thoughts I'll share in case they're of interest.
* Getting two gunners makes me groan as much as having a second pilot. Three will make me quit the match if they won't change before it launches. But three engineers I'm content with, especially if they listen when I tell them what ammo to bring.
* A good gunner is awesome. But I've found most gunners can't really shoot, even with the Hwacha. As someone else mentioned, it comes down to that whole keeping ship momentums and stuff like that in their head.
* A good gunner on my quad-hwacha Galleon can be pretty devastating. They can disable most ships before they can really do damage, and if they slip over or under, switch to the other side's guns and take out those engines. Buuuut...
* I pug pretty much all the time, can't seem to get a consistent crew together. Most gunners suck. I'd rather have 3 engineers (but definitely a minimum of two), cause when a gunner can't do the above and disable a ship's gun, you really can't get by with 1 engineer holding the ship together. Stressful times, you really need two and ideally a third that can try to get a gun up quick.
* I have tried briefly and would like to try guns besides the hwacha (or hellhound on my Fish), but I can't count on having a gunner that can hit dependably or, honestly, even at all.
And lastly...
I'm not going to try another role any time soon, I think. If I did, I think I would want to try gunner. Mental math on trying to hit two moving objects, using the ideal ammo, that sort of thing's of more interest to me than just trying to figure out what to hit with a wrench first.
But there's just too many gunners already.
Fortunately, many will switch to engineer when I ask them to (though I feel kinda bad doing it). I myself, meanwhile, will be staying at the helm. Piloting in this game's interesting, at least : )