The IT's were much easier to live with than the YZ's. Yes they had heavier flywheels for more inertia and chug in the woods. Better spaced gearing for woods riding, and tuned for more low-end. That being said, they are NOT wimpy by any stretch of the imagination. The big bore IT's are absolute animals, they'll climb a tree if there's enough traction. They don't turn real well (long wheel base, heavy) but very ridable bikes...love 'em!