If you are buying new, no concerns. If you are buying used, and are looking at a 6.0PSD, spend alot of time reading over at www.thedieselstop.com in the 6.0 forum and van forum.
An advantage of a Ford van is how long they have been around. Everywhere you go you will find mechanics who are familiar with them. Small towns in remote places (Canada, Alaska, etc.) may never have worked on a big Nissan.
Alaska to Key West, Labrador and more
Prostate cancer survivor. See Thread Prostate cancer and Sportsmobiles
2015 VW GTI 2020 Fiat 124 Spider
2012 E250 Hitop camper
Just an observation since I also own a 08 Nissan Armada ... the 5.6 motor with 5sp auto and 3.23 gears can haul my 6000lb Armada quick and fast. It is a lot quicker than my 06 E350 RB 2WD with 5.4, 4sp auto and 3.73 gears. (Admittedly, the van is probably 500+lbs heavier and shy a gear.)
For me its way too early to know the long term durability of the 5.6 motor. For the 5.4 there are reams of input and testimonials.
The semi-float Dana60 is what it is. Don't overdo it and it'll treat you fine. Upgrades abound, full floater D70s, even D80s. The Armada has a D44 and I couldn't find what an NV will have. If the NV has a D44 ... I may ask a lot of questions about long term durability and load capacities. The Armada/Titan forum members have been begging for a factory D60 for quite some time.