In a simple way, each kite has best L/D ratio at a specific Angle of
Attack and flap i.e. brakes configuration.
So it is possible that by releasing the brakes you get better L/D until
some point and then fall back. The opposite may be true too ! You have
to find your optimum setting. the same applies to AoA (sheeting in/out).
So thats why you see opposites things on differents kites, in found on
a 4 lines Wipika that the kite goes higher as you sheet in. If you
sheet in too
much it just fall back a bit.
I think luffing means less AoA (wich can lead to higher or lower kite)
not reduced L/D (kite falling back for sure)
If we want to learn more, we can read about airplanes wings, those kite
do fly and we can learn a lot from what has been done for airplanes. Of
course we have specifics requirements but that an another story.