Satchelis, you might consider two different kinds of tires. Loaded on rough roads will put the sidewalls on the rear tire through more work assuming that's where most of your weight is. A slightly larger front tire will make off road riding more controllable. A fast comfy set up could be a 1.6" Sport Contact or Supreme on the rear with 1.5"- 1.75" Panaracer T-Serv on the front.
Steepness of paved roads has no bearing on tire choice, that's pretty much power/weight ratio. Tire type can make as much difference in rolling resistance as size. The Panaracer T-serv and Sport Contact feel like faster tires than the Supremes. I put 2.0 Supremes on my LHT which had 1.75 T-servs and noticed it was a smidge slower. Once the bike is loaded up it's kind of academic given that weight on any incline has more significance than rolling resistance.
Last edited by LeeG; 05-24-12 at 07:47 AM.