I am also a new owner of an 05 28A+. I have a 97 f150 with the 5.4l with 3.55 gears. On the highway it's fine, but I see what your talking about with the hills. If it was me I would get a set of 3.73's installed. $400-500. If you like your truck its the cheapest option. Now if your looking at buying a new truck..... Ford! Bad experience with Nissan when I had problems. A lot of passing the buck around. I know there are going to be others that say the same about Ford, but go onto www.titantalk.com
and read about the braking problems and rear end problems going on. Not to mention "my favorite" the bent frame from towing a toy hauler.
P.S. I hear Ford is coming out with a new f150 for 09. A set of gears could buy you some time until they come out.