First new truck, old one was a 2006 Chevy 2500 Duramax. It is not a good comparison powertrain as the Duramax can pull massive loads and power is way above the ecodiesel. Fuel economy on the other had is much better with the Ram eco diesel.
In the 1500 class truck, I think a 4.0l engine would be a better balance for towing and still have good fuel economy. The 5.0l Cummins going into the Titan this fall or early next year will be another game changer. It will be interesting to see what they certify the fuel economy as with the EPA.
Ford has a mothballed 3.0l diesel and 4.5l diesel that will most likely make its way into the F150 within 4 years. GM also has a small V8 diesel that may see action in this segment as well.
Ram started a good thing, but the competitors are definitely taking notes. If the consumer market is receptive, we will see many more diesels in the truck segment.
Note: The GM Colorado will have a 2.8l diesel next year that should be over 30mpg.