Just my experience -
I used a Terry Fly for a while... it was fine on short rides (below 100 miles), though I did have some numbness issues. On long rides it was absolute murder. After a 12-hour UMCA event, I actually found blood in my bibs from chafing. I now use a Brooks Professional on my touring bike and my tandem, a B-17 on my rando/distance bike, and a Selle SMP pro on my racing bike.