But if one is considering a FES glider then the performance differences between the fuselages of the V3 Sport, V3 Performance, and JS3 are less relevant given the performance loss from the prop on the nose. See the Idaflieg Lak 17a FES report that shows about 2 max LD points (4%) loss and 3-4 kph slower at typical cruise speeds at the same sink rate. It would make no sense to me to try to squeeze into a small cockpit to gain significantly less performance than you are losing from the prop.