I know some people who have used seal and glide and had really good results. One of them did a before and after porosity test before and after by putting the fabric over the top of a bucket and polling water in it and leaving it for hours to see how much came through. Before the treatment all the water went through quite fast and after pretty much none so it does work in some ways. I have also get a kite after application and they really do feel much better and seem much less porous. fwiw I think you should keep going around kissing kites RE porosity and air perm I am more concerned with my old flysurfer taking on water if a crash it and relaunchability which seems to be improved with these treatments.