RE: new vs. old slalom shapes
I'm not Ian but this is what I can share: I started sailing slalom boards towards the late 90s when shapes were still comparatively long and narrow. Today I'm on a modern short and wide board and for me the most noticeable difference is how much more free of the water the new shapes ride, particularly in chop. The older shapes could ride free as well but it seemed to me only in flat water. THe new shapes have much shorter rocker flat which is I think why they feel this way. I figure the shorter rocker is compensated by the wider tail shapes so early planing is not so affected. And for sure the range of the new boards is outstanding. I use one board in up to 30+ winds on a 5.5 and the same board in winds less than half the strength on a bigger sail, with a fin change of course, although a change up to a larger board would probably be ideal. I find the newer shapes easier to gybe as well. It feels it's because there is less board in the water so there is less board to deal with in the turn.