I played both the demo of X3 and the babylon 5 game, and neither seemed to have true space physics. In X3, the craft only kept going in the same diretion for maybe 3 seconds, and it was soon corrected somehow by the game automatically. Maybe I am missing something

For example, when you roll, it is a "star-wars" roll. The craft rolls at a constant speed and stops when you let go of the joystick. It just seems like they made it so you get a little velocity in the same direction when you sharply change pitch.
I haven't played the bablyon 5 one for a very long time, but I remember the physics didn't feel right. There was an "inertia mode" IIRC where all that would happen is you would keep traveling in the same direction if you changed pitch or roll, and there was still a lot missing. I haven't played in awhile though.
I am still waiting for an absolute, true space simulator with physics something along the lines of
orbiter. All the ones I've seen are kinda headed on the right path but have yet to actually get there. They seemed to be star wars physics meshed with true zero-gravity-zero-friction physics for a half-baked 50% experience.