I have done the parks the past 2 years that weekend. Friday - did MGM, went to 2nd Fantasmic, was about 3/4 full. Park wasn't too bad, but didn't get there until dinner time
Saturday - Epcot - 75 min waits at Test Track; everything else was 15 or less. I would hedge to guess Soarin would have long lines as well. This is a busy day, but Epcot can hold more people than MK so it was never overwhelming.
Sunday - MK - about as busy as mid-May. Most people start leaving this day. By Monday, the parks are not too busy, although it was busier last year than the year before, but I'm not sure if those were displaced hurricane travelers or additions to that time of year