Congrats on the new purchase! The biggest issue I have with ANY new diesel is the DEF system. Diesel exhaust fluid systems are sort of problematic at this stage of the game. At least where GM vehicles are concerned, I am very skeptical of the reliability of the set up. I can't really speak of the Mopar systems... I hope that they have a little better service than GM.
However, for your application I do agree that a 3/4 or 1 ton is the best option for you. The suspensions are made to take the kind of abuse that you will be putting the truck through. A half ton just can't live up to it's potential using it on a heavy duty setting. A 1/2 ton simply does not last in a farm use setting, which I would think would be fairly similar to the type of use that a snow plow would require. The engines in a farm setting seem to last ok- it's all the suspension parts that can't stand the test of time. If these two are not similar? Well, I am from Louisiana- I don't think I have ever even seen a real snow plow! lol