That having a gunner at all is controversial is an issue. It should be indisputable that having one of every role is optimal, and that's just not how it is right now. I don't know how you manage your crew, but on my ships everyone stays near their battlestations, my engineers aren't wandering off far from their guns or relying on each other to trade places on their guns for different situations.
It's just so situational. Everyone can always use a full repair kit, it's situational when you can use different ammo types. Proper planning can drastically reduce the needed ammo - carronades can get away with just having charged, burst on Manticores so long you fly with teammates so you're not trying to fight another Manticore in which case you bring heavy (the extra uptime and selfbuffing is a REAL help as you have time to buff EVERY shot). I really look for excuses to use a gunner whenever possible but I'm responsible for all three of my crewmembers having fun and that often means actually winning those close matches, I hate having to tell someone that they need to switch roles. If the light guns could benefit more from different ammos, then having even two gunners could be very competitive rather than the near death sentence it is now.
I think a lot of the problem is that there's very few ammo types that can work on any gun. Ammo choice, as it is right now, is commonly dictated by the captain or just inferred when the gunner looks at the loadout. There's one, two, possibly three ammos that work well with the guns they'll be using. There's not a lot of room for variety, and ammo variety is the gunner's one strength. It's not fun just taking what the captain tells you to take, you should be able to mix and match to your preference without impacting the captain's plans at all. I should be able to say something like "take something for accuracy, hull damage, and disabling" and just let the gunner choose based on comfort and his own skill.
