Bruce,

I sail the Taipan, same mast as the Blade. Standard dogma is to rotate the mast 90 degrees going downwind. I differ from that.

The aerodynamic purpose of mast rotation is, of course, to keep the flow smooth and attached to the lee side of the mast and main, making a nice, smooth transition from one to the other. I've found that with the Taipan/Blade wingmast, 90 degrees is actually too much rotation for the apparent wind hitting the mast/main when the spinnaker is up. Of course it depends a bit on how hot an angle you're sailing too. So downwind without the spinnaker I rotate 90 degrees; but with the spinnaker my rotation is usually less (unless very light air) than 90 and rarely over 80 degrees. My main has tell tails just behind the mast that I use to set the rotation.

In general, I've found the wing mast likes less rotation on any point of sail compared to a tear drop profile mast.

I don't rotate the mast to avoid some kind of structural mast failure--it's plenty strong and should be fine as long as you keep the main cleated.

Incidently, did you sail one-up? If so, you and I both understand that setting rig just right can be tough with only two hands.