Haven't towed mine in the hills yet, but it behaved just fine coming down the Jersey shore to Virginia. I couldn't feel a significant difference between my old monster Chevy Silverado 2500 Diesel (2008) and the new 2013 Ford F-150 Ecoboost 372 rear end.
To be totally honest though... I towed the new 25 Eddie Bauer home without all my crap in it. I have cleaned out a lot of stuff that I wonder how I ever collected, so it will be a while (if ever) before I load down either the A/S or the tow vehicle with the stuff (weight) I had on the Safari.
Tows nicely. I'll head to visit Sister Karen in Ohio - and the mothership - sometime in September. That will test it through West Virginia's mountains.
It's a heck of a better daily driver - turns in only 3 lanes instead of needing 4 in the opposite direction