I don't disagree with the gist of that post and I deliver Airsteam TTs with my EcoDiesel. An 8,000 pound boxy TT is a load and on the upper limits of EDs reasonalble limits IMO at least for towing the western grades and many depending on their driving habits would be happier with a 3/4 ton diesel for that load. If you use your truck for a daily driver and don't tow that load regularly and don't need to be in it to win it. The ED can be an excellent pick.
I do frequently deliver 31' Classics that are 7,800 (their biggest) and comfortably tow 65 to 67 mph for fuel economy and range between fill ups to make good time. My truck has the 3.92, a GDE tune, (for an extra 30HP 55TQ, turbo brake plus plus)& a 31.9" tire and I rarely have ever had to go below 5th and 55mph on any grades and I have done most of them. Its a responsive truck and gets even this load moving from a dead stop to highway speed respectively. But if you are running into the wind or climbing a grade at speed with that load you will realize its not a big diesel.
Knowing where peak torque and peak horsepower are and watching the tach with this load peak horsepower doesn't come into play often with the 8 speed. Well unless you are determined to lead the hammer lane. So I guess I don't get the HP numbers hangup thing. The trucks not slow unless your are moving something outside what should be done with a half ton platform in the first place.