The theming at the Poly is great, and I love the pool, etc. But what I REALLY go to Poly for is the transportation options. Being on the resort monorail loop, being next door to the TTC for the direct MK and EPCOT monorails, and having the MK boat, make it the best resort in all of WDW for transportation purposes.
I'm willing to pay a pretty good premium for this transportation, although I always go during value season, so I try either the Poly, WL, or even BC.
But $1,300 is a LOT of money to consider, when really, transportation options are really the main reason to stay at Poly instead of CBR. I'm sure CBR has a very nice pool, as do all of the resorts. But remember, the first week of December is not all that warm in Orlando. Unless you're a polar bear, even heated water can be tough to deal with when the air temps are in the 50's and 60's for the most part.
If you want a half-way priced option between CBR and Poly, I'd get a quote for WL. It has the really nice ferry boats to MK, and has the best theming in all of WDW, IMHO, and it supposedly has incredible Christmas decorations.