Here is a Magic Find FAQ someone posted on Reddit with what has been found so far:
http://www.reddit.com/r/Guildwars2/comments/zsbvw/magic_find_and_you_a_brief_faq/
Here is data (300 kills 0% mf vs 300 kills 100% mf):
http://www.reddit.com/r/Guildwars2/comments/10547v/i_am_back_with_more_magic_find_data/
Of course, none of it is “official”, but I think it might be useful. Make sure to read dssurge comment on the FAQ.