What is the difference between the two spins? Is one flatter than the other, or does one have a shorter foot, or longer luff or leach? Have you laid them on top of each other on the grass, just to see where the major differences are?

I've got a fat one, and a flat one but I prefer the flatter one as I can reach up higher and get the boat up on one hull quicker, then bear away and keep it up on one hull easier.