Well I disagree with a lot of your points. First off most of the failures are the crappy designed EPA mandated parts, not the engines themselves. The part, left alone can do engine damage, on some models.
The EPA sets standards with ZERO idea if those standards can ever be met, and it's one hellova job for the engineers to design a system that works AND will hold up.
Second, my daughter is one perfect candidate for a small truck/diesel combo. She lives in the city, but likes to bicycle and take the dog with her on walks and runs, so a truck is a big bonus. She, like me does not like getting dog hair in your face as you drive down the freeway, so the dog rides outside.
The Ecoboost does not compare mileage to even the Ram 1500. Ever hear of anyone getting 19 mpg towing 7000lbs with one? Didn't think so. Most just get 20 unloaded. Then to get 30 MPG when empty is icing on the cake.
Fuel costs? Uhh wrong again. Here in CA most diesel is at or under the 87 octane gas. Where I buy mine, diesel is 3.99 and 87 is 4.11. Prices on fuels fluctuate based on stockbrokers whims so that can go anywhere.
Based on prices I have seen on Ecoboost trucks, the diesels are no higher. Not sure about your area, but they are pricey here.
Emissions systems are evolving as well. The Ford 6.0 was a Navistar engine and so was the 6.4 but Ford knew their relationship had come to an end, and was not happy with the poorly designed systems they put on it. The new 6.7 is a Ford engine, and has had little issues, thus far.
GM just recently got a patent on an electric DPF system, that does away with the need to spray piss in your exhaust (urea based DEF) and will put the heavy trucks back in the low 20's for MPG, and the small cars and trucks in the high 30's and 40's.
I do not understand the logic in saying they are cost prohibitive, when you look at cars like the VW Jetta TDI with 45-48 MPG. My neighbor has one and he only gets oil and filter changes, never needs anything else. BMW now has 7 models of diesel cars, and most will be available in the US. Nearly every manufacturer will be offering diesel in the next year or so.
Efficiency wise, the gas engines will NEVER produce the power for fuel consumed, that diesels do. Horsepower does not do the work, torque does, and gas engines have to have far more displacement or fuel to provide it. As for running out of steam? What speeds do you drive? With the newer 8 speed transmissions, most light diesels are coming with, there is a ratio for any road condition or speed any sane person will drive.
Diesel performance is achieved with the crappy fuel we get as well. Gassers need the 91 octane to get anywhere close power wise, and the cetane levels for diesel fuels is pathetically low compared to Europe, where 60-70 MPG in a diesel sedan is not uncommon.
Plus an ignition system failure is one less issue to worry about.