It definitely won't be as smooth as the first 2 games, just as going up was REALLY weird in the original titles. The engine uses anything but "real physics" and has been built around giving a satisfactory feel going up, classic mode uses the same engine and it just shows.

There's talk of doing a modded version of LtF3 to bring back horizontal gameplay, gliding and stuff to destroy though.

Patience young grasshopper. Patience.