I've converted KHMovement for Litec last week and now changed the trace to c_trace. From the manual I see there's a P before the USE_AABB and made me think its a professional feature? Must I remove USE_AABB from the code? When I do it makes the player bounce a little on the ground like he was on a trampoline or something like that ^^

From my understanding yes. USE_AABB is a professional feature. However, I am not sure how USE_AABB is handled when used in a version that doesn't support AABB. I DO know that achieving the desired collision effect usually requires quite a bit of tweaking.

just try and find optimal collision mode

Yes I always try, but thought it was a Pro only feature. Although it seem to work with A7 Commercial too.

I always thought that P stands for Pure, no wonder I don't see any difference on whether I'm using USE_AABB or not.

... <no comment>
Before someone insults me.