Very true, but I'm thinking nothing really noticeable in someone's collecting lifetime. Long term/conservation wise, I wholeheartedly agree.
UPDATE: I did find an experiment someone did where it appears the UV glass didn't offer any kind of protection. It was from 2002 and I didn't see where they mentioned the brand. I may have to conduct my own experiment using some throwaway darker comic covers. Anyways, here's the link: http://www.ukiyoe-gallery.com/sunfade.htm
and this is an interesting discussion on the subject: http://www.thegrumble.com/index.php?threads/uv-rays-glass-and-pompous-physics-majors.504/