Sorry for the delay with responding to this question.
The old design with the wedges is good, but lately I have dropped it due to being un-necessarily complex. The wedges don't contribute enough to make it worth all the extra work and hassle was how I felt. Watching people struggle with the shape of those wedges I really felt it was too much hassle.
I would say that 6 x 1 is too thin for an eight footer really. I recommend inch and a half minimum there. Could work for a six footer though. Scaled down. However I usually go for a slightly slower blade with more torque for six footers as the bearing friction starts to become an issue for startup.
The designs in my recipe book are worked out to be effective and easy to make, so that's why I recommend them, but the older plans work well for what they do (apart from the 12 footer in the older book that I regret to be honest, although a lot of people in low wind areas have had good results with that design too).
I like the wedges myself but it's more of an aesthetic thing to be honest I am not sure they really do much good since that part of the blade sweeps very little wind.
The recipe book is now out in a kindle edition that you can get for only $5 off amazon. the snag is that I have only done the metric version in Kindle thus far.
