I've been using SD for some years now, and I like it a lot.
However I miss the possibility of seeing the glide distance in planning mode. As I live in at country with a lot of water I often need to zigzag my route to stay in gliding distance of solid ground. To do that I use rulers and calculator to lay out the route.
It would be so much easier if it was possible to "turn" on glide distance along the route in planning mode.