I have a set, but so far, my longest run was a 9mile trail with only a bit of chunky rock area. It was pretty darn smooth. Going up hills felt weird, like I was wasting a lot of energy squishing the foam instead of pushing off the ground.
All in all, I like them, but have no interest in the road version. Ultras on road just do not sound very appealing.
yeah, I think they are made for real gross downhills, which is why I got them. I might run with them on the days after a snow storm, when the snow is all crusty and pothole like, otherwise a lot of overkill for the road.
I got them for the long trail runs. I always feel fine on the descents, but the day after I am completely trashed. They are supposed to be good for quicker recoveries.
That said, the first time I ran with them, I landed on all the rocks I could find, and only those pingpong sized or larger had any sensation.