Good point, my reference is mostly Warthunder and their derived stats, if pressed I would've dropped my upper range down to 200m/s- but, and this is the best part of your point, energy loss while turning/climbing would bring things down a lot closer to 100-150m/s and the way space jam and acceleration seems to work right now ships will be able to maintain maximum speed through turns, so top-end speed is more of a constant factor here in this game than real life. As to how that's going to alter and gamify the combat sequences, I can't say, even small variables in performance can really swing optimal behaviors around, let alone changes to the physics engine, so I won't make any significant guesses until we can get in and play around.
The only hard guess I can level atm is that, given acceleration isn't really a factor in player-applied physics currently, everything is a turn-fighter and the slowest ships will be the anchors for furballs- meaning big/slow things are going to represent the boundaries and center of a battlefield that faster things will move around and trigger reactive maneuvers from the other faster things. Assuming my assumptions are close to correct, having the slower vessels effectively become terrain details for the faster, it's a good thing that ships are more often disabled or decrewed than destroyed.