Just went over this the past few months. I decided to hold off for a lil later, when I'm not looking to buy a home... You can check the thread here with some good advice from the other guys.
The 2011 Doo's are wicked from what I understand and have only gotten better. The biggest thing is the ETEC, which is direct injection. They perform way better and get way better mileage. After that they made some wicked improvements to the suspension and handling from what I hear. Some of those can be put onto the 2011's to upgrade 'em but a sled that's almost brand new is gonna be nice enough that you may not even care that much. Up to you.
Everyone says get an 800 with a 154 at least for deep mountain riding if you're in the rockies, so you're on the right track. Seems like almost everyone around here rides Summit 800's, that's most of what's on the used market here.
2007 GNU 11up 162w / 2012 GNU Carbon Credit 162w / 2013 Lib Tech Banana Magic 158w / 2013 GNU Eco Genetics 162 / 2013 Lib Tech Birdman 180
2007 Burton Custom Brew / 2013 Burton Malavita / 2013 Malavita Restricted / 2014 Now Drive
2013 Burton Ambush / 2014 DC Travis Rice