I enjoy these discussions about the relative merits of different power/prop setups. I transitioned from an Osmose/Pletty/21x14 to an Inspire/V3 contra, then Agenda/V4 and now a Angelit/V4. For me the contra is about ease of speed control. I'm fortunate to have Joe Walker as a flying buddy and he alternates between a Fantasista/Pletty and an Agenda/V4. He flies both well but as I coach/critique his flights his speed control is better with the Agenda. I believe therefore that the contra's benifit is speed controll, not decreased left turning tendencies. Which then opens the question, might a single prop belt drive not offer the same advantages ? As a strong believer in the KISS principle, I'd prefer to get rid of the extra prop and mechanics required to drive it.