Just an update - I just used these shorts for my 200 miler this weekend and they were great. It was a huge leap of faith for me to use an untested (at that length) chamois on a double century, and they were great.
I'm taking a pair to PBP. I turned my friend Lesli on to them and she's got 2 for PBP. They really are a fantastic long distance short. So supportive!