Insofar as Greenlees and Chitty are concerned, AlanF and others provided extensive info last year at http://www.jehovahs-witness.com/6/5466/1.ashx
integ, Ray's credibility is as much a matter of the receptivity of the reader as it is the documentation and tone of COC and ISOCF. Your question reminded me of the "over 500 at one time" eye-witnesses that are recorded as seeing the resurrected Jesus. (1 Corinthians 15: 5, 6) Even the WTS notes that many scholars attribute these post-resurrection experiences to "mass ecstasy." (w3/15/01 p. 4) Where do we draw the line? How many witnesses, and what types of credentials for those witnesses, are required before an historic account becomes "credible?" Sheesh, the Mormons only have 7 eye-witnesses for the golden plates, but that's good enough proof for several million people.
What it boils down to is "what do I want to believe, or not believe?" Most JWs don't want to believe that Ray, or any other "apostate," is telling the truth; therefore, in their own minds the bar will be set as high as it needs to be to reject whatever evidence (WTS-letterhead communications, personal testimonies from hundreds of others who "were there," etc) is offered.
My experience: just keep casting that bread out on the water...let them take whatever they will, whenever they can. In my case, it took over 10 years for the accumulating evidence to break through to me, and I fought it every step of the way.
Craig