I would take it. 66K for a new H1 is a great deal. HUMMER dealers are selling the leftover H1's at extermly low prices, I heard how they are now able to do this, but I cant remeber why nor would I be able to explain it in words that anyone but myself would understand.
If you look at what private parties are selling used H1's for they will only be a few thousand less (if that) then what your dealer is asking. The other plus to buying new over used is that you get a full warrenty. Whereas if you buy from a private party you will only get the remainder of the warrenty. I love my H1 event though its been a money pit (wish I could afford a new one) there is something about that truck that puts a smile on my face every time I look at it.