I think the Frontier is a great choice. The cab is roomier than the Taco, and the ride and interior noise level is better as well. On the whole, a more pleasant place to spend mind numbing hours on the pavement getting to your destination.
I have had the opportunity to spend a fair amount of trail time comparing brand new 2012 Taco's to a 2007 Frontier. I was greatly impressed with the Frontier. The Taco in question was the latest and greatest, off road package, traction control, rear locker, etc..., but was completely stock. So was the Frontier. What impressed me the most, was that despite less overall ground clearance, the Frontier exhibited a significantly better suspension set up, with much greater articulation and better absorption and rebound control as well. I was also impressed that the Frontier's older TC system was not in any way inferior or slower in responsiveness or effectiveness compared to the Taco's traction control system. I think with a mild OME lift (2.5-3"), decent tires, and some armor, the Frontier would make an excellent vehicle for overland travel.