going from a 6000lb TT with my old 1500 with 3.21 gears (which NEVER gave me any issues pulling or sway etc) to a nearly 10,000lb TT with my new 3500 w 3.73. Tossing up the 4.10's was hard. I do a lot of non-towing driving and was nervous about gas (lol, I do realize this is like ordering a Diet Coke w a bacon cheeseburger and fries!) but, like the diesel, I didn't think I actually needed it. I pick up the TT after the holidays. We don't do any significant towing untill next season. we shall see...
In hindsight I sort of regret not getting the 4.10's. but, having the truck now a week and a day and 600+ miles, the MPG is pretty bad so I likely would have kicked myself on that if I had went w them. Bummed there was no real numbers to compare before I purchased. End of the day, my truck gives me the buffer I wanted - I'm more than good for what I need it to do.