More tq than a hemi at lower rpm means more HP where you spend all your time driving. The eco diesel weighs about 20lbs more than a hemi so the weight difference is pretty much moot.
There are already tunes available for the euro engine which uses the same Bosch ecm, so I highly doubt it will take 3 years. http://www.bluesparkautomotive.com/carspecs2?carid=6585
314 max hp/ 527 max tq with just a tuning module out of a 3 liter.
You drive a lifted truck with big tires, wouldn't you like to get better mileage with the life and big tires than the hemi can get? Not to mention a gas truck with big tires drives like crap without the gearing change to accommodate said tires, always hunting for gears, revving up and bogging down when it upshifts. Granted, this shouldn't be such an issue with a tight ratio 8 SPD trans.
The eco tows more than an equally equipped hemi, 9200lbs vs 9050 in a 2wd long bed regular cab configuration with 3.55 gears. It will out tow the hemi completely if a 3.92 gear set is an option when it goes into production.
Lastly, in your words, "fuel is the only thing". The only thing is a HUGE thing! An eco should beat a hemi with the same configuration by 5mpg, going off the info currently available. Not to mention that the resale of the diesel will be much higher than a hemi truck (based off a trend with 2500&3500 diesel vs. Equal gas models).
Forgive me if I fail to see where you have proved your point.
To the other people in this thread, I realize the diesel won't be for everyone. I've driven hemis. I've owned gas trucks. I've owned diesels. I think the hemi is a fine engine. I just have a problem with someone making ignorant statements about something they haven't driven or even seen yet.