I also went back and forth on which gear ratio to get. Two things sealed the decision: liking the FX4 (style & off road features) and my typical driving (commute with lots of stop lights & 50-55 mph speed limits most of the way).

From what people have been reporting online it seemed like in my typical drive the highway benefits of 3.31 or 3.55 gears wouldn't really make much difference. Also I test drove the truck I bought, which confirmed this thought.

Once the gear ratio was relegated to secondary, the other features made the decision. From limited time at highway speeds it looks like it will get 18-20 mpg highway, and commuting it will be 15-17 mpg (depending on traffic and lights). Stop and go around town looks like 12-14 mpg. But less than 700 miles on it so far, so still breaking it in.