I sold my '04 Renegade 800 with 6000 miles and bought an '07 Attak last Feb.
I wanted to go 4 stroke, have a 136" track and still keep the rider forward seating. The Attak was the only solution last year. There are trade offs with everything but if off trail, deep snow riding is what you do most, the Renegade is better by far.
The Attak rides better on groomed trails but darts awful. (So did the Renegade with precision skis. I changed them to Simmons. Much better). The Renagade handles deep snow great. The Attak will go but trenches awful with the ripsaw track. You can carry extra gas on the Renegade but not the (stock) Attak. The Renegade uses a LOT of injection oil & gets 12 to 16 MPG. The Attak uses no oil and gets the same mileage. The Renagade is WAY better on big bumps. The Attak has too much rebound and the heavy nose shows. The Attak, with running board coolers has a heating issue in low snow conditions or trail riding at 40 degrees with no snow dust. (See threads on antifreeze concentration, water wetter, rear cooler & ice scratchers). The Renegade never bothered. I have 162 Woodys 1.325 Mege-Bites in both. The Renagade cooler is in the tunnel so no overheat issues with it.
Having said that, I only got 900 miles on the Attak and have made some changes that I haven't tried yet. I added Simmons Flexi-Skis (for deep snow) and have Bergstrom carbides, ski savers & shims coming for the stock skis (trail riding). I pulled the limiter strap down a hole, added Hiper-Fax with SLP wear pads on the closed track windows, temp ga, and the Mono-Shock is being revalved by Pioneer as we speak. I reduced the antifreeze concentration from 85% stock to 60% and added water wetter and ice scratchers. I gave up on the auxillary cooler because of the cost, weight & potential contact with the picks.
I expect the revalving of the shock, skis & limiter strap adjustment will make a different sled out of it.
You would LOVE that four stroke engine! The Ski-Doo will run very rough at low speed (who cares?), smoke when it idles, backfire when you shut it off, make the right side all covered with sticky guck from all the oil it uses but it was dependable and didn't foul plugs.
I know this is more information than you asked for but I had a chance to compare the two sleds the same winter.
If my changes make the Attak a little better in the rough and float better in the deep, I will never go back th two strokes. The Yamaha quality is great and I don't think I will have the feeling that at 6 or 8 thousand miles I should be getting rid of it. Very nice machine and works very well for 90 % of the stuff I do.
TimC