Your choice of a truck to consider as a tow vehicle is a great choice.
The 6.7 Powerstroke went on sale in the 2011 model year and has received some great updates for the 2014 year.
You have already been given some "don't buy because" posts from a couple posters here.. :h
If you do any searching you will notice a common theme of negative posts on every Ford 6.7 thread from certain posters.
Even though the entire forum is about RVs, it seems that some members only post on Ford 6.7 threads and ignore most other stuff about RVs, destinations, issues with RVs, etc.
Kinda makes it seem they have an agenda and its definitely not "to help" RVers in general.
The Ford Superduty series trucks with diesel engines outsell both the other brands by a large margin and though there have been some with issues, be assured there are "FAR" more happy 6.7 Powerstroke owners than any other brand.
Choose your dealer wisely and your experience will be great.
In fact a poor dealer is what actually caused one of the negative posters issues, but he prefers to blame Ford.
I followed his original issue closely and really thought Ford would help him out, but something went on behind the scenes and they bailed on him.
That's why I say to choose a good reputable dealer who will back you and look after you.
Good luck whatever you buy.
Any of the new heavyduty trucks from any of the brands will do a great job today, but don't be deterred by folks with an axe to grind if you are leaning toward the Ford.
2000 F250 V10 dragin a 2005 Titanium 29E34RL