"Assuming you could get the right deal,"
this is the magic statement! YOURS is more or less "new" - yet out of warranty......so someone that wants one used is going to have to see your price as a bargain compared to a zero % loan on a new one!
I would say that you would shoot yourself in the foot if you traded it to the dealer, you would be better to sell it on a craigslist or somewhere - then again, you will have to put up with that too.
I would imagine that a new one will cost you 22k ish???
and you might sell your machine for 17K ish???
You can figure the the new new models, lets say the 90 series are 3-5 years away, so there probably will not be any really neat new features for this series for a few years.
It all depends on what you are willing to do and how much money is needed to "upgrade" to the newer model.