Dave,
I've got an '09 Renegade X with the E-tec, and I couldn't begin to speak highly enough about it. I put about 1800 miles on mine last year and it was flawless. It starts instantaneously, absolutely sips injection oil and gas, and there really isn't a smell or smoke when riding behind it (cold or warm engine) as I have a buddy I ride with who has this engine and we both noticed that immediately.
The summerization process this Spring was interesting and very helpful (it fogs itself automatically with the correct sequence of button pushing). You can't even buy spark plugs for the dang thing, as you have to be taught how to change them.........the ones that come in it are guaranteed for (I believe) 10,000 miles. Obviously fouling them out isn't too much of a problem!
I don't off trail ride, so I can't speak to the engine there (the Renegade is a very highly sought after "cross-over" sled so this speaks for itself), but IMHO this engine is every bit as powerful performing and feeling as my 600HO SDI, and as I never want or need to ride faster than 90 mph (which I've done on the '09, and there was more there to get if I had wanted it) this thing provides me with snow heaven; great responsiveness, proven reliability (Evinrude outboards for 5 years before taken to the sled configuration), great economy, the Ski-Doo great styling, so again, I can't say enough about it.
Hope this gives you a track to run on Dave. If I can answer any other questions, let me know. I'm sure others will chime in here too.