I've read enough on the truck forums over the years, as they have been dealing with DPFs and such since '03-04 and there is a never ending stream of complaints about the emissions equipment and what it does to reliability and fuel consumption. I expect this to be similar. I have a close cousin who was an engineer at Cummins for 30 yrs and got many an earful from him about the downsides of the emissions standards, too. The only upside to it is some degree of cleaner air. How much, I do not know.
The other things I see are the compromises they had to make as a result of the new requirements. The lack of room under the hood requiring them to move the fuel tank is an example. I think that is a bad location, and the filler neck is just asking to get caught on brush and limbs. My tractor spends a lot of time in the woods, so that stands out really big to me. Another big compromise is adding another $5k on the price. YEEE-OWW! Have they added some nice features? It sure sounds like it, but I'm not willing to trade the downside of the Tier IV emissions for the nice features. One man's opinion. Before long, there won't be a choice if you want a new tractor, so everyone will have to adjust to it eventually. In my case, I expect to keep this tractor for life, and that suits me just fine.