The Corvette is not exactly "manouverable", although its clearly better than the Cutter in that department.
The Cutter on the other hand, if tougher. As better shields and armor. The Corvette packs a stronger punch, the Cutter can withstand a larger beating. Corvette turns a little better, Cutter has far greater speed. Cutter is also a better multipurpose than the Corvette. Corvette is theoretically better one a one-on-one fight, Cutter is better at all other roles besides combat. I've seen videos on youtube of Cutters winning against Corvettes, so its not impossible.
The Cutter may not be an all-out warship. But it presents more alternative roles. And that way we get more alternative uses for new ships, instead of 2 new equal ships with different colors. That's fine by me.
Also, it was time for the Feds to finally have a bit of an upper hand at anything, they had been the underdogs (in terms of faction ships) for almost a whole year. Let them be on top for a while.
Due to more useful internals and the power issues of the Cutter their on paper defensive stats are pretty evenly matched. But the Corvette is not "a little more maneuverable". It can out turn a Conda, and a Conda has ~ 40% better pitch than a Cutter. And since maneuverability is a multiplier of a ships defensive and offensive capabilities the Corvette is actually far more defensive. The Cutter may have a bit better shields, a bit worse hull (with HRPs), but since all ships regenerate 1mj/s (or 1.5 with bi-weave) not getting hit is the first form of defense.
And of course they can win in some PvP. A viper can take down a Corvette. Does that make the Viper a better ship than a Corvette?
And, in terms of PvE, the Cutter is much, much worse.
Oh, and a multirole can effectively fight. The Cutter can not.
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The Empire may have had better ships for ~ a year, but that doesn't mean it was the right move. What's more, at least back then, it was well known that more ships were coming. As it stands, the only word regarding these ships is they are the end of the line for large faction ships.