I went hiking/trailrunning in my VFF's today, went about 5 miles. They were great...the only oddity was that I didn't have as much heat resistance as I was used to, and if we were taking a break, I had to stand in the shade.
We went out to the San Tan State park, home of Boob Mountain.
Crompsin, here's some side shots.
As you can see, the heel cup isn't totally flush. I could possibly go down a size, but because my heel doesn't touch the cup now, it doesn't bother me.
The flexibility of these shoes is amazing. Here's me picking up a rock with them.
It was a great day for trail running.