Re: [JFK] Sail/Mesh slider...
My impression also has been that sail slliders offer less consistency than mesh sliders. This seems to be true in terms of heading performance, and also altitude required for an open canopy.
A friend of mine has back problems, but managed to make it through a 3-week trip to the big walls in Europe with a mesh slider (large holes, I think) and careful rolling of the nose on his vented canopy. I really can't imagine a situation in which I would choose to use a sail slider.
Michael