don't know anything about changing board sizes.
However, after watching most of the video from typing nacra 17 into youtube….i am ready to race. ha ha.
Anyway it looks like my original comment about the video above has flaws; sorry for that.
The edit to "slow mo" of the boat lifting up made me perceive a huge loss in speed. Actually it looks like they didn't loose that much to the boat below them. That boat could well have been the reason the blue boat headed up in the gust instead of bearing way off like they needed to. Heading up causes any cat to lift the bows and that seems to be multiplied with the curved boards. Blue just flogged the sail for a sec, held onto the boat, and took off with out too much slow down.

In one video, a hot shot was saying that they stand further forward because of the curved boards. If they lift the boards up partially for heavy wind, they loose that extra lift and have to stand all the way back to fend off the pitchpole. There is one video of an orange team pitchpoling 2 or 3 different times while sailing with the boards in the partially up mode. If they just use them in down position, maybe by just bearing off at the perfect time in the perfect way----then easing it back up jus right, it would likely be fast to the downwind buoy; in everything except racing in max wind conditions where they seem to have to go partial up mode.
A situation that winglets help with. For me, that winglet is like a leg to stand on. You can really rely on it's stability. You are standing on that little wing that has constant lift even when power in the sails is varied. Maybe it's a training wheel, but it brings a higher level of control in the dicy situations.

There isn't much question that a decision would have been made to keep the rudders simple before they released the boat. It's still a fast cat that looks better than all the other ships on the olympic course, and will take real skill to win races on. The boat is very camera worthy in the videos. -not a fan of the single hulled, except when they are definitely faster, or for surfing/jumping.