I've been giving this some thought as well. I am by no means an expert on surfboard design and fin placement, but it's obvious that they toe in the fins
for a reason.
My 5-8 rnf Lost has tri-fin with toe-in. I like the way this seems to make the board pivot. I also feel like I can sometimes get better upwind performance in light wind/marginal power by "scalloping" or doing mini "s-turns" to build board speed/apparent wind...carve up.. burn down...carve up..etc. The fins
seem to propel me upwind very fast on the "carve up" phase. If I hold a straight line going upwind the board seems to bog down a little if I am not more active with it. Maybe that's just lack of experience?
When kiting many people tend to ride in a straight line more often and perhaps the toe-in is not optimal, but for turning and reaction on waves I wonder if straight fins
will be a disadvantage.
I've also thought about putting a rather large swept fin in the middle and smaller fins
in on the sides.
I'll be interested to hear about Freds experiments.
I imagine the answer to this dilemma is like many other things, such as a sailboat: there is not one boat design that will do everything well.
...that's why we have to have lot and lots of boards....hehehehehe