My indie mechanic (who I stopped using for reasons unrelated to the sunroof) lubed it. When I asked what he was using, it turns out it was vaseline. That's fine with me if it works. I also use the sunroof regularly, based on the "use it or lose it" principle, and am careful that if I have to close it while driving I have the windows cracked open to avoid any unusual air pressure. I still haven't done any inspection (relied on the mechanic for that).
I have a 2007 too, sorry to hear about your exorbitant replacement cost, hoping to avoid that! (Knock wood!)