While I don't think "last edited" is particularly useful and I prefer to focus on simplicity and what really matters, I don't have a strong opinion either. 

However, I do have a strong opinion about trying the use of "volunteers" rather than "editors". While for us wikimedians "an editor" sounds almost as familiar as a friend, for a big percentage of our readers, an editor sounds like a literary or newspaper editor, like someone almost professional and erudite, "not like me". "Volunteer" is an accurate and actually more descriptive term, which sounds a lot closer (and should I say human?), and sounds "like me" for an interesting portion of our readers.