Jim Crandell has a testimonial on PSA's website. It's also worth reading Ken Kendrick's and Brian Seigel's testimonials in light of the Mastro T206 Wagner PSA 8 debacle.
http://www.psacard.com/About/Testimonials
The problem I see with all of these testimonials is that there is a an on-going theme of blind confidence with no persuasive proof of PSA's ability to detect alterations. Nowhere does anyone say, "I deliberately doctored some cards to see if they would get detected by PSA and when I submitted them, PSA caught each and every type of alteration."