I fully agree with what v10superduty posted. It helps to have a capable person in fleet sales that actually understands what the options change on the vehicles. I researched as much as I could on my own prior to the purchase and had fleet go over the configuration. The only change was to not select the FX4 package due to shocks not designed for weight handling and just order the skid plate package with stock shocks.
I do feel a weaker engine having to pull hills will wear on the driver more than one that has more reserve under the pedal, but you have consider how often you want that extra capability. My buddy pulls a large boat across the mountains two or three times a year to vacation with family. With a smaller vehicle, the five hour drive would fatigue him to the point of wasting the rest of the day sleeping. After two seasons of losing so much vacation time to sleep, he upgraded to a vehicle where he comfortably makes the trips and can be on the water the same day with energy to spare. The smaller vehicle was able to haul the load, but it took so much more driver energy to keep it under control and maintain speed. This may become a moot point once we are retired and have less time constraints, but until then we need to keep our work/life balance in check and use our time off efficiently.