I think sailing a Nonsuch is quite different in many respects than sailing a sloop. For example, a vang isn’t a basic necessity in a sloop or other Marconi rigged boat. It’s a fix for a drawback in the design. An expert like Ron can turn it into a tool on a sloop, but it’s one that we don’t have or need. I have been using the choker more and more and I do think it makes sense to think of it as a sail power controlling tool. Our sails (mine anyway) tend to form a really clean shape. With the wishbone passing below, but close to the C/E of the sail, it can be used to add or remove power without changing that optimum shape. I have been experimenting with that out in the ocean in fairly constant winds and I can often see half a knot or more difference in my speed within seconds after an adjustment.
I have been using this regularly to get me through the 1/4 mile or so zone where Point Loma accelerates the wind. Last week we were in that zone, paralleling the Californian (130’ schooner that could easily leave us in their wake if not carrying tourists). My friend wanted video of the schooner, but another boat was between us. I asked him to ease the choker quite a bit and we shot from 7.2kts to 7.8kts (GPS). Once ahead of the other boat he tightened back up and we slowed to a more comfortable 7.2kts and he got a nice bit of video.
Edit: the 8kts in my original post was a typo due to cut/paste error on my little phone screen. It was 7.8kts as I’ve corrected. But we did hit 8.2 kts twice that day and spent most of our 6 hours over 7kts. That friend is more energetic than the usual “crew" who go out with me, but I have hit 8.2kts on a couple of other occasions. That seems to be my top speed as I have never exceeded it.