Yes the originals were kind of junky, but the kept the "ultralight" speeds in the legal area.
From the website:
The Ultra-Prop blade has a very simple airfoil and planform with no aerodynamic or geometric twist. The selection of this configuration has a story too long to reiterate. Suffice to say, it works very well on many ultralights. Unfortunately, the injection molds to make a longer and more sophisticated blade, along with the associated development and testing, are prohibitively expensive. If all goes as expected, we will introduce a new 66" diameter Ultra-Prop with a sophisticated blade design by Craig Catto in 2016.
So yes apparently they have a new blade design, And shoot, for the price, it might be worth a try.