There was a question in one of the threads about which one is better in longevity. Here is an article from Sep 05 issue of Popular Photography that may shed some light.
http://www.popphoto.com/article.asp?section_id=4&article_id=1492&page_number=1
http://www.popphoto.com/article.asp?section_id=4&article_id=1492&page_number=1