I,m not the best person to respond to this, as I have had mixed reviews with my testing of the right spot. I feel 5-10 degrees off straight (drooping side of head)is about right, but I have tried all kinds of angles, and it is hard to tell which is the best. If you have low winds, this will be more easily determined, my winds are rarely mild, so it's hard to pick.
Imsmooth has done a video and comprehensive bunch of pages on blade carving with a chainsaw. http://www.mindchallenger.com/wind/bladecarving.html
I would recommend you view that as well. I still think that straight twist and taper is the best compromise for these kinds of alternators (Imsmooth thinks otherwise)... and the chainsaw likes it better too.
But seriously, an average blade I think does better at mixed TSR, rather than designing for a peaky TSR (perfect calculated blade)... and never running at it. I suspect (but don't know for sure) that the peaky blade will drop off efficiency faster as it moves further from design TSR (the straight twist and taper blades we chainsaw built for the AWP seems to back this up.... performed better than the fancy originals)
If you intend to use these things in partial stall operation as the Dans do, this should be more true. (which is why they do so well with this design parameter perhaps)
I would use their description of blade dimensions from their book/online story as the basis of my blades.
If you intend to use mmpt, then proper blade design would be an advantage..... if you could live with the high RPM.
.............oztules