I tow a boat that weighs under 4000# on the trailer about 3000 miles/year. I didn't opt for the tow package because I don't need the trailer assist, as I can back up just fine. The difference between the two axle ratios is about 11%. The difference between first and second gear is 36% for the 10-speed transmission, the overall difference between first and tenth is 7.44:1. I was comfortable that the transmission would more than compensate for the relatively minor difference in rear axle ratio. The standard radiator is more than up to the demands of towing the 6000# the truck is rated for without the tow package, so I saved the $1500. And, I'm getting over 20MPG average, so I'm happy with my choice. I really don't care about spirited driving in the truck, I have another car and a few motorcycles for that.
IMO, the tow package isn't really necessary if you're not towing heavy loads routinely.