Yes, I've read a number of is threads and replies. He definitely seems knowlegable,... and prolific - over 10,000 posts I believe.There's a very knowledgeable fellow over on the Gearpage.net who is a tech in Scotland (named John Philips) and I read a post of his a while ago in which he listed all the factors that determine an amps tone and he actually listed the tube type quite far down the list. I believe that it went something like:
1. actual circuit design
3. Cab construction
4. tube type
Maybe you could do a search over there. I find most of his posts to be good reading.