4.7s started in 00 and as long as the normal maintence was preformed they are fine. I have had 3 4.7s and all run fine and have had them from 2 miles, 18 miles, and 30k. They took the place of the 5.2.
when it comes to jeeps, durangos I would have no probelm with getting a 4.7 as long as they were taken care of. From 2004 the Hemi came out in the durangos and they were great.
In order I would take a jeep from years 1998-2010 --> 4.7, hemi, 5.9, 4.0
Durangos-->5.9 till 2000 then the 4.7 (2003 had all wheel disc brakes and a some small odds and ends) Gen II-hemi, then 4.7
Rams--> CUMMINS, Hemi