I have been to both, 2XTree last fall.
There is no comparison, I would take the Tree any day of the week. It is a very nice property; kind of a trick to find, it is in the middle of an Office Park setting but a very nice hotel.
Remember, virtually all HGI's are purpose built while very few 2XTrees are. DoubleTree is the Hilton Brand for rebranded hotels, that is one reason I like them so much, always different inside and out with a consistent level of quality.