I guess that's where we are -- adventurous -- because the people in my family who sail the Taipan 4.9 with spinnaker leave the mast rotation set basically the same for downwind as it is for upwind, and no positive mast rotation is used. We just basically let the mast rotate to where it wants to be, which seems to be about 45-50 degrees.

Are we living on the edge? Well, at least we have been warned by people with more experience and engineering know-how than we have.

I would guess that the most common causes of broken masts when sailing with spinnaker are mainsheets being inadvertently released or positive mast rotation devices not being released for a jibe.

P.S. I still would like to know what the difference is, as far as mast rotation recommendations, for a masthead spinnaker versus a fractional spinnaker - but maybe that should be a thread on the main forum rather than here.