RUdl
That was an interesting read, however a few things come to mind after reading that and doing a little more searching and then re-reading.
The non-popularity may come from the need to engineer fabrication methods and then building an actual device.
When this "study" was doned there was more modeling done using computational methods than real work-horse type testing.
If you take a look at the wing style and the fact that there may be the need for specific overlap or gap or a combination of both , this design may not be in the realm of most DIY'ers.
While this style does seem to have benefits over the larger wind speeds even the speed they have are far higher than a great number of DIY mills are built for.
IF you setout the build a unit with this profil, I for one would like to see the 3-D mock-up and subsequent testing in winds ranging from 6mph and above.
Bruce S