Joanna,
I think the luff on the Goodall spin is a little shorter, 6-8 inches. I remember that you guys moved the block on your mast down when you made the change. I moved the pole a little higher because I was sailing uni and not using the pelican striker. Mine seems to work fine, the same as the Glaser. The vipers carry their spin pole higher than the blades. Maybe that has shifted your sheeting angle a little?