The Stealth, as you know, has high(er) aspect boards. I've found that solo in a blow the boat's much happier on threequarters or even half boards.

Downwind in all conditions I'll lift the boards, less in lighter conditions than when it's blowing, but never more than half up. You need to retain some grip on the water, as Matt says. If you get a puff downwind without boards the boat just doesn't accelerate as well and if you then try pointing up to accelerate the boat just overpowers and trips in.

I've tried sailing downwind several times with full boards but it's just too much like hard work. The boat is too 'grippy' on the water and flies at the slightest change in apparent.

Just my experiences as I see them......