Just so you all know - I upgraded from a 1500 to a 2500 years ago, just for hauling this TC around. And towing the bike trailer. And have always advocated 250/2500 for TC hauling - safety the most important reason, of course.
But, with the truck changes over the years, am investigating the options - for a variety of reasons. In part, availability, ability to bargain 1500s better than 2500HD, and a good point earlier, the RMV costs as well.
My best guess at the moment - I'll stay with a 2500HD, and feel very safe. But, it just occurred to me that gathering new information about new technology and new engineering never hurts.