I'm actually glad I didn't get the Hemi, although the last (and only) one I drove was in 1971. I haven't timed it, but I'm convinced that my 4.7 regular cab 4x4 is faster 0-60 than my last three fast cars...a 97 Lincoln Mark VIII (stock), an 02 Mustang GT with an x-pipe and cat-back, and an 06 Monte Carlo SS (stock). That's fast enough for me.
I've been through 3 1/4 tanks of gas so far, and with 30% city and 70% highway driving, I'm averaging a little over 19-mpg. Had I bought a Hemi, I can assure you with that temptation I'd be averaging about 10.
Another reason is that after I do my first oil change with Mobil 1, I'm not going to have any reservations about going the full 8K-miles between changes. Had I opted for the Hemi, I don't think I'd want to stretch it that far.
The final reason I opted for the 4.7 is that I just don't like the idea of MDS. I know it works, I know it's proven technology, and I know it's seamless and all the rest of it...but I just don't like the concept. I didn't like it in my Monte Carlo (which never averaged more than 22-mpg), and I know I wouldn't like it on any other vehicle.
I didn't buy my Ram for the mpg, but I do use it for a fairly-lengthy commute. Once I get a few miles on it (and switch to synthetic), I fully expect to average 20-22 mpg...which is a whole lot better than I'd get with 390-hp on tap.