I was planning to do my pemi loop in June/July but I've been battling a bit with injuries and haven't got the miles in this spring. I think I'm going to reschedule it now for early Sept, since I'm going climbing in Toulomne in August. I'm just shooting for something like 14 hours for my first try, and will be happy just to finish it no matter if it takes longer.
I agree with your assessment of the 100 mile. I only hiked it, but I thought despite the lack of serious climbing/descending the footing wasn't great except at the beginning and end. I remember lots and lots of erosion with terrible roots for miles on end through much of the middle section.