FYI, many non apparent cats have vangs. When going downwind square with the traveller and main sail all the way out, it is important to keep the boom low to present max sail area to the wind.

My old Dolphin had a wing mast like a super wing and never experienced any promlems with rotation. Also had a vang on my old Mari 4.3. Paper Tigers, Mosquitoes, Arafuras and Quickcats I have also sailed had vangs.