just about every pair of my shorts, and I've got at least six different brands, has irritated me at the edge of the chamois. On last year's AIDS ride I developed horrible blisters.
Today I rode with a pair of chamois-less shorts -- a pair of sugoi compression shorts with no padding and the skin seems pretty good in that area-- a little red, but no pain.
The ride was only 20 miles and I'm not sure I'd do well on a longer ride, but I'm really not sure what to do.