I ran 4.75's w/ 35" tires on my DII. Loved the higher RPM. 70 mph was around 3K. Made the vehicle feel reasonably responsive.
Downside is I broke the gears my first trip to Moab. With the Rover centersection, it means to get that ratio the pinion gear is very small, allowing it to flex under load. This in turn causes the mesh between the pinion and ring gear teeth to get out of line, and the end result is ring gear teeth being sheared off.