It's very likely that the port to the new engine causes some side effects in movement. For 0.9.0 I was planning to make them closer to 1:1 alongside the Portal-related movement abstraction (among the Fortress Forever import as well).
I've heard crouching for the TF jump modes also feels off, which is odd but might be how the crouching is handled in GO engine.
I've also heard that rampbugs at higher tickrates seemingly don't happen on this weird version of the movement currently as well. We might want to keep that for the TASers! But expect the movement to change a bit more as we approach 0.9.0!