With a flatter main you're not maxing out cunningham as quickly. When you are maxed out you can keep it sheeted harder for longer before you have to start sheeting out and footing off to keep the boat rolling. Not talking about gusts here. I haven't felt short on power in lighter air either, but I do adjust diamond tension on the water if conditions change drastically.
Matt says you can get them result through spreader rake, and through diamond tension, and yes you can flatten the sail dramatically, (and if you go real crazy you can make the top really fall off), but I was really hunting for power when the wind lightened up with those settings. I think I took it to 42 on a black Loos gauge, and something like 2-1/4" of speaker rake. It was an obscene amount of prebend. Hindsight I don't think any of those numbers is safe for that mast, but it did survive.
When I started to sail A class I went through a bunch of sail iterations. I am short and light, so overpower is a big issue, same as the uni guys experience with the F16.
I had several different cuts made built out multiple different bend mast and borrowed a bunch of others trying to find a formula that would make me competitive to weather once the winds started up over 12. After a bunch of money and effort, I realized that changing sail cuts made approximately zero difference in how I was performing.
Once you sail is pulled flat, whether is early or at the end of your Cunningham range, it makes no difference. How you run the sheet and tiller to maintain hull speed makes all the difference. Apparent wind is your friend just like the problem TEH was having in another post.
I would love to sell everyone some dedicated equipment and the sail makers would too, but if you really want to play with it, creating a bit more prebend will flatten out the bottom of you sail earlier, and some stiffer battens will work the same in the top. 20 minutes of time and a few battens are cheap. Problem is a flat sail to start then has limited power in the light stuff. I have been very happy with the standard sails we have already. The very bendy masts used on the F16 allow you to have a very full sail and within the range of control, I can still pull it board flat. If you still need less power then really you just need less sail
