I just reread and edited my post. I think I had turbo on the brain and left the "diesel" out!
The 5W-40 is not a diesel designed oil. Soot, high CR's, longer drains, new low sulfur fuel, generally longer piston stroke, etc are some of the stresses on a diesel oil.
If one of the worries is the lab won't have a baseline, you can send a virgin blend in, but honestly with the $20 analysis it doesn't matter much and if you are really that worried send them through Terry.
As for the two oils, I'm really hooked on the AME. The HDD is a good oil, but is overpriced. I have several runs on the AME and think it's a great value. Blending the two isn't to outsmart the Amsoil chemists, it's to fit an oil precisely to your car, something Amsoil doesn't think about much.