In my limited experience with spi's on a monohull, I have to agree with you that some lee helm downwind isn't a bad thing, although if it's too much I would guess it might set you up for an accidental gybe if you let go of the tiller for too long at the wrong time, especially in waves.
I agree with you that two CB wells would take too much time to manage if you were racing usual courses and if you tried to do it at the time you hit the mark; I acknowledged in my post that it would take more time to change over from upwind to downwind. This is, of course, unless the change was done on the flying hull well in advance of hitting the mark when there's time to do it and at which time it would't have adverse consequences.
Actually, in my original post, I was curious if two wells would work well for cruising, recreational sailing, and long distance racing where it might offer a very light touch both upwind and downwind for long legs avoiding any strain on the skipper, and in the case of long distance racing, might offer a slightly lower drag and more efficiency which could add up to slight performance gains over the times and distances involved.
