A sign of the apocalypse!?!
Sportsmobile referring people here? Must be because they already have your money. Just kidding. It's great that SMB is sending people here, probably because we'll talk you into spending more money on options.
I've an '06 diesel (6.0L) and have had two minor problems both corrected under Ford warranty. I don't have one and haven't really followed it, but I believe the 6.4L is even more reliable. I will say diesels can require a bit more attention that a gasser (minor warm up, cool down, fuel additive).