While the gunner role gets an innate trust when it comes to being a high level, I feel that an actual bonus should be included with the role. Whenever I join a game, I never choose gunner because of how restricted the role is- his or her primary role is to shoot, and the secondary role is to keep their gun functional. If something gets destroyed, the gunner has to just sit around and wait, or feebly attempt to help out the ship with whatever repair tool they brought. The engineer's role is to keep everything functional, and secondary role is to use a gun whenever there is downtime.
Most of the time when I play gunner, I simply use a long-range ammo and a short-range ammo, like lesmok and greased. While it would be nice to have both of these, I always end up using one clip of lesmok as the distance is closed, then I stick with the second clip for the rest of the engagement. Having the extra ammo is nice, but most of the time, a gunner will sit on the main weapon of the ship(heavy gun of the spire, goldfish, front gun of any ship, really), and that main weapon will only really benefit from a particular type of ammo, like heavy, charged, or incendiary.
My point is that an experienced engineer can fill in the role of an experienced gunner, but no other classes can really feel at full strength in any other role. If the gunner received some sort of utility bonus that wouldn't break the game, like extra zoom levels on guns, increased move speed on the ship, or some other sweet candy, it would definitely be more of a draw to use the guns as a gunner instead of an engineer.
