I traded a 2006 2WD 2500 5.9L diesel which was a great truck, for a new clearance 2009 2500 6.7L diesel 4X4. The difference is like going from a prop airplane to a new jet. I was concerned about the emissions problems (clogged DPFs, turbos, etc.), but I bought an August 2009 build (the last run for the 2009s), so it has the latest computer firmware, DPF & turbo. It does have the tag hanging from the dash with basic instructions on how to drive the 6.7L diesel so that you hopefully avoid throwing codes and too many regens. My normal errands run is 60 miles round trip inlcuding a 30-45 minute interstate/freeway run, so the emissions system should function OK. I'm also going to tow a TT.
6.7L Cummins has great power, & is very quiet. Exhaust brake works great. 6 speed auto with the manual button mode is fantastic, a quantum leap from the old 4 speed auto. Stock radio is pretty good, & I've had premium sound (display's a little small.)Short WB, drives like a 1/2 ton, tows like a 3/4.
Most issues are addressed in the 2010 models: updated interior, more comfortable seats etc. A 2010 would have cost $15K more (no rebates), and they're just starting to arrive at the dealerships. If you have the bucks, go for the 2010, they're pretty awesome. Same motor/trans/emissions AFAIK.