I've been watching the starship poll and thinking about the way ship classes are currently handled.
What a lot of us don't like is being forced to abandon our canon ships in order to advance. I think this could be solved, along with where to slot in new classes of ships without resorting to ship costumes.
Treat the class group as a "master template" that can be changed once anywhere in its division track, similar to a respec.
I can't think of a less wordy way to put that, so here's a scenario. You hit RA5, and your choices are fleet escort and advanced escort. You pick, say, fleet escort. You default to a Dervish with the consoles and abilities that you'd get normally with a fleet escort.
But there's another drop down, a "master template." You can pick everything down to a vanilla escort. You get penalized, of course- your ship stats follow the master template, not the ship category. So you choose a Saber to use as a fleet escort. You get your consoles and your abilities, you get your weapon slots, but you also get the ship stats of a Saber- power output, crew, hull, turn rate, etc. Also, you have to stay in the category track; you can't just add fleet escort capabilities to, say, a Galaxy or a Nova. And it goes without saying that you can only use up to the tier you've unlocked.
The pros are more variety in levelbanded areas. Strategy would be likely to be required more, since there would be a much bigger variety of ship stats in PvP and the like, and we wouldn't be forced to abandon our favorite ships.
There are cons, too. Weapon slots are still an uncertainty. A Saber outfitted as a fleet escort might have some balance issues because of its added speed and agility. Also, the Miranda group would be pretty hard to fit in this way, as it's really got elements of both cruiser and escort.