We went through Poughkeepsie and the dreaded "Wall" without a problem. Completely unscathed. 1-2 re-positions at most and all were running open-diff.
A little more information about the trails on the website would be useful.
A 2wd w/o low range could easily do Alpine Loop, Cinnamon Pass, Minnie Gulch, Ophir Pass, Imogene Pass, and the Yankee Boy Basin (with possibly a little help). The others, a 4wd in high will suffice.