Where are you running your mast foot?
There could be some mast foot tuning that can help your board to go faster and ride more smoothly.
I had my mastfoot in a forward position, the outer diameter of the mast foot was just touching the vent screw. I have done this on this sail after I started to get into the footstraps. Because when plaining in less wind, the nose got to high and the board stalled, and I wasn't able to plane. But I guess if this is what it is sopposed to feel like when you are fully powered up, I could try to move the mastfoot slightly backwards to get less wet surface.
But sometimes I get a bit frightened when the gust hit the rig and I go real fast, because I am afraid of loosing control. But I think that more TOW will give me more confidence, to just use my weight and hang in there. It is fun to go very fast as well as a bit scarey