to all,
As Wouter and others note, the max downhaul is bending that mast above the hounds to the max also, opening up that leech.
Also, as mentioned, the mast rotation is minimal, so the related downhaul induced mast bend is on the long axis of that mast.
Further, it may be or not, the top 3-4 battens may have been switched out for solid glass ( re; no bend) battens, due to anticipated wind conditions. The only reason for this is to control power ( inhibit it) at that part of the sail plan. I read about this( and other tuning tips) from an Aussie T 4.9 champ, which can be found on the F-16 forum on this URL.
By looking at the way those battens are acting ( no bend seen), it would be a fair statement to suspect very stiff battens.
Uni sail/mast control is an entirely different realm and it is great to see these experts set up their rigs for different weather.
great sailing!
regards,
Bruce
St. Croix