I towed (heavy) for the first time today with my SD
 

I've pulled a gooseneck horse trailer twice now moving horses, but that's fairly lightweight. Today, I delivered a tractor we had for sale. The tractor weighed around 7,000 pounds, and the goosneck trailer was about 4,000 pounds. The V10 handled it well, and the truck was rock solid. I had a lot of weight forward of the trailer axles, and I run Cooper Discoverer STT's. They behaved very well, with no sway at all. Having experienced towing a decent load on flat ground, interstate, winding mountain roads, and narrow, single lane back roads, I am very stocked with the truck, and do not regret switching from diesel to gas. I really appreciate this truck.

I am on my 2nd V10 and still love it. Well except when I replace exhaust manifolds

Good to hear your truck performed well for you. I have pulled that much and more with my 5.4 and it handled it just fine, and I am sure your v10 handled it much better. I tried diesel for a while too and have no regrets about getting rid of it and keeping my gasser.