Amsoil's marketing dept. is the secret to their success. Back 5 years ago I ran Ams Dominator in my sleds, not because of scientific proof, but mostly because it was advertised as being the most awesomest. All the cool kids were running it in their snow cross sleds, and I liked the sweet Amsoil stickers.
As far as running synthetic oil in your diesel trucks, if for nothing more than your own piece of mind then by all means go for it. In my own findings through analysis (w/ both Blackstone and MI Cat) Rotella T and Chevron Delo LE dino oil held up just as good, if not better than some of the fancy synthetics when pulled with anywhere from 5k to 10k miles.
The bottom line here is run what you like, regularly scheduled maintainence is key no matter what oil you choose.