I don't have this plant either (sorry, I know you want first-hand responses), but one way to see if a cultivar is fertile, or a great parent, is to see if and how many child plants it has had over the years. Dragonfly Blues has one child plant, and it was only registered in 2010, so at least it is likely fertile. Two years is fairly quick after an introduction, so there may be more child plants down the line.
