Averages
The averages during the time you had originally scheduled are about 75 for the high, and 55 for the low, with record highs in the mid 80's, and record lows in the mid 30's.
The averages during your 'new' vacation dates are around 82 for the high, and 63 for the low, with record highs in the low 90's, and record lows in the mid to low 40's.
I almost always schedule a trip for the first week in November - it has usually been pretty nice at that time, though I've been surprised a few times with how warm it has still been.
One huge advantage of your 'new' dates is that you will be there during the tail end of the EPCOT Food & Wine Festival, which is my favorite Disney event of the year (and has been for many, many years now). However, you are most likely too late to get reservations for many of the best 'hard-ticket' events that go on during the festival. (there's still plenty of 'regular' Festival stuff for you to enjoy though).