I was strongly considering MT/Rs on the 4Runner until I bought a set of Duratracs from Joneseyyy. I always ran MT/Rs on my 05 Tacoma when I had it and I loved the tires. Excellent handling, great off-road capability, and they lasted forever (I got 60k miles out of one set). However, since running Duratracs on the 4R I decided that they aren't worth the extra cost despite how much I like them. There's also a 5lb difference in weight - MT/Rs being heavier of course.
I don't think you can go wrong with either tire. The Duratracs seem to have a more consistent pricing scheme and MT/Rs are typically more expensive. But, I just checked on Tire Rack and the MT/Rs are only $40 more for a set of four.