I knew you would show back up....I drive one because I can, plain and simple. I don't like taking a 1/2 mile to pass a damn FEMA hauler draggin a bowed axle piece of crap BIG TEX trailer down the road. My gas pickups wouldn't tow up to my expectations, so I wouldn't aggrivate myself any longer. However, my every day driver is a gas pickup (company) and so is the wifes. The less I drive the 3/4 ton, the less it cost me. At this point with 30K miles on my wifes Envoy and the same on the diesel, The gas maintenance is roughly $300 and my truck is $600. Where are the savings? Hey, I own both so show it to me dude.
As far as you four banger debate goes, I believe that the difference in purchase price figured out to running 380 hrs or so to break even buying a four stroke. So about 4-5 years of operation, more than that for most people.