Total conjecture, but I've seen on Reddit and RSI's subscriber forums that it will probably be something between Gladius and Hornet. The Hornet will still be a tank, but the Sabre will take nearly the beating and be able to out maneuver it. Not as fragile as a Gladius or as maneuverable, but packs more punch and takes more flak in the mean time.
I went back and watched the live video again, and man they need to work on letting us land smoothly. The Connie nearly tipped forward twice. I had trouble mapping the vertical thrust to a rotary switch like I do in Elite that lets me set down softly every time. Seeing the way they take off (jerk up, stop, jerk up, stop) drives me a little bananas. I was hoping for better after seeing the Retaliator land gracefully in the Gamescom demo.