I think an even more important disclaimer next to wind would be waves. The wind speeds at Zandvoort where around 19 knots, waves betwee 90 and 110 cm.
The waves made if very difficult to accelerate and keep speed -> apparent wind changed constantly and big gusts hit you from the back.
On the Blade you really need to get the hull flying in bigger winds to my opinion (just not sure yet on how to generate enough wind without steering to high). If you fly a hull you just can't stuff the bow anymore in gusts. If you sail it flat, you stuff the bows easily when bearing off.
