I caught on to the two-rail diesel models after watching Rich Battista's video "It's All About The Trains!" I bought an ABA set of Premier F3's with one powered A unit in two rail. It will be the lead engine in the consist. I don't run on track curves that are narrower than O-72, so tight curves are not a problem.
I love the look of fixed pilots and scale-sized couplers in scale-sized pilot openings. I have very few "modern" diesels such as GP's, SD's, U-boats, etc, so that type of conversion is not a concern to me.
I'm pretty deep down the rabbit hole on this. It started with putting body-mounted Kaddee couplers on some of my rolling stock, and just grew from there!