In free running there are alot of cases were is best to not even touch the object in an attempt to gap something. A good example is Mirrors edge you can tuck them as to get enough clearance to be out of the context of the grab the rail animation and as a result your arc through the air is longer. Ex. clearing a hand rail to reach a gap higher than the rail.

I am not aware if this has changed, since the Brink Compendium has some errors
http://www.fragworld.org/frag/brink/the-fragworld-brink-compendium.html

"A. No air crouching, but the vaulting and mantling take care of most of the cases you'd need air crouching. Plus, the lower the ledge is relative to your body, the faster it will be, so in effect, you get the same speed benefit in pre-jumping a vault. i.e. in the examples you give, you'd always do a vault, but when you do anything to hit the vault higher, you'll decrease the duration of the vault move."

Like repelling a magnet? would there be a Loss of momentum if you hit low with a high camera orientation? I know that they said you momentum would carry through, but your saying its mildly tweakable?

I don't know if there has been anything that specific revealed.

[Edited out a misunderstanding]

Doing moves manually in combination with the SMART button is said to give the best freerunning results.

Crouch Jump (Halo) ?

Crouch Jump (Counterstrike) ?