I have a Formula 100. It's basically a Pure Drive with slightly less power and slightly more control. I have seen a number of people say they found it to be more powerful than the PD but I don't find that to be the case (I have a 2012 PD also).
The main advantage is that it is way, way more comfortable. It is incredibly solid feeling compared to the hollow feeling PD. Much better on the arm as well. I have more confidence with the Formula than the PD, probably because of the feel.
I demo'd the Pro One 18x20. It's a bit heavier than the Formula and more control oriented.