What I recognized is, that if I switch between the old and the new one. It would be great if we find a way that each icon has a fixed unicode number. Otherwise the users will see another icon when they update to a new version. I think that´s impossible with fontello. I will try with fontforge. Maybe there is a solution for that. And I think it´s cool if the filename is versioned like the icon realease 1.1 and so on.