Coming up the east side of Crabtree was easy peasy. Nothing more than class 2, at the worst. When we were up there we went around the cirque and up to Discovery Pinnacle so I cant comment on the west side of Crabtree Pass. The view from the top down didn't look difficult, just appeared to require the usual care in picking your route. If you've done the MR on Whitney, and were comfortable doing it, I don't think that you'd have any problem tackling Crabtree Pass coming from the west side. From my experience the MR looked a lot steeper than Crabtree from the top.
