If I were you I would stick with the earlier travel dates - and possibly move them back even further - for two years now we have gone around the 1st week of December and the crowds are very low - and being DVC members - we have been able to get exactly the reservations we want - for our resort AND our dining. The longer you wait to go in December/New Years - the larger the crowds and the higher the prices.
We love going in early December - it REALLY puts us in the holiday spirit - we use out Annual Pass discount to get all our Christmas shopping done - plus the crowds are practically non-existent AND we stay where we want - and eat where we want!
PLUS you can sometimes get great deal on dated merchandise - I don't care if my sweatshirt says 2010 on it - I saved $37.00 on it!!!! I would never pay full price for Disney clothing - it's outrageous - but with the new year coming - they want to get 'old' merchandise off the shelves! The same applies for pins too!
I SOOOO wish we could push back the dates, but with the kids in school (7th and 4th grade) we just don't take them out for vacations and I help run our family business and the week before Xmas is so busy for us that I felt guilty about leaving my parents in a lurch without my help...they would never say so, but I know I saw some relief when I told them I was most likely going to cancel the trip and re-book for the week after Xmas.
This will likely be our ONLY trip to WDW for Xmas and I wanted it to be so special...I am bummed now.

I remind myself (as the kids shopped tonight for the angel tree children they picked at church today) that we are so blessed to even be able to THINK about a trip like Disney at Xmas and so blessed to have been able to go in October and in April years ago that I have NOTHING to be bummed about for sure!!
We just sure love our WDW time!!