Comment: para 4 - "When people who understand WCAG 2.0 test the same content using the same success criteria, the same results should be obtained with high inter-rater reliability". More than just an understanding of WCAG 2.0 is required - these people also need an understaning of how PWD interact with the web, with or without assistive technologies.
add something extra to the qualifications that WCAG 2.0 testers are required to have to obtain the same results.
Also suggest changing "high inter-rater reliability" to "high inter-tester reliability"
The qualifications to be a WCAG 2.0 tester are not formalized, and the quantification of knowledge skills and abilities to do so is beyond the scope of this document. We do agree that a qualified individual should have background in disability and not just the web.
We have revised the conformance section significantly since the April 2006 working draft. The sentence related to your comment, in http://www.w3.org/TR/2007/WD-WCAG20-20070517/#overview-sc, now reads:
"The same results should be obtained with a high level of confidence when people who understand how people with different types of disabilities use the Web test the same content."