I love the Paleo Diet and am hardly a pussy in the gym. Check my profile for links to my blog.
As for the fiber comment, Loren Cordain mentions frequently throughout his book that Paleolithic peoples regularly ate 100-150g of fiber a day, and recommends an exceedingly high fiber intake. I've never gotten that high, but I've gotten into the 70-100g per day range.
If you want a brief rundown of the Paleodiet, I've got one on my blog:
http://chaosandpain.blogspot.com/2009_02_01_archive.htmlCombined with Metabolic Typing, Parrillo, and newer studies showing that megadosing protein can be highly beneficial, it's definitely useful.