I just entered the 55 plus category, and looking ahead to 65, it's hard to imagine going as hard  as I do now.  Just as I know it's noticeably harder now than it was at 45.  Lord knows I'm working my tail off.  So it seems that after 45 or 50, it would be a bit more fair and beneficial to make it a 5 year age group.  Personally, I don't mind people knowing my age either, so it'd be nice to see a person's age in their profile so I know if I'm competing against a young kid or not.