"So in the real light winds edging just kills the power."
In the really light stuff you have to ride cross wind for a bit first to get your board speed up and then edge and turn up wind (takes more skill than it sounds) another big tip is to not choke the kite by sheeting in too much too early. Wait till you have the board speed up going cross wind first then start edging to turn up wind and then you can sheet the kite in more once you have built up more apparent wind and you are pointing more upwind.
The fins on your Sector will look big compared to the ones on your surf board but compared to the 30,40 and even 50cm fins on some of the full on race boards they are tiny

I ride 26cm and 28cm fins on my Monaro V3 and that rides flat or edging on the leeward/toeside rail but i think that is more to do with the volume/shape of the board than just fin size alone.
Biggest killer of performance on the smaller free race boards is the weight placement. It is a very common mistake to have too much weight too far back on the board and sinking the tail. You have to keep the board trimmed!
So is it just you our there racing the boats TH or are there a few kiters getting into it now?