I was at the REI garage sale today and on a whim picked up a newish North Face Ultra 110 gtx for $50. I loved the deep treads on it and it seemed to have good foot support (though not as much on the ankle).
I did Whitney last year using a Vasque hiking boot and it killed my feet on the descent. I have been reading about trail running shoes and am seriously considering it for this year's trip.
I have most trouble with my knees and ankles on the way down. I have given up on ankle high boots giving me enough ankle support, so will be relying on ankle braces.