I think it is a combination of physical ability and breathing technique... sometimes certain body parts just dont fit...(big teeth or not). The breathing is correct. Without this technique the body thinks it is suffocating and will act accordingly... not panicking and remembering to breathe...that's purely mental. As for the natural lube...yup thats true. a true DT will produce (in my experience) that good old D*ck swallowing lube which seems thicker than normal saliva. I'd take that pepsi challenge...win or lose..it would be a hellava lot of fun.
Average guys getting the blues? To be honest... you guys have more of an opportunity to get really massaged. An above average guy, while being accommodated, may not have the same experience. A beautiful thing about a well versed throat is that, if not at maximum capacity, it has the ability to pulse and squeeze with the remaining space. It isn't that you don't want a gag reflex....you want to be able to control it. Just like vaginal muscles, they can be exercised with practice.
In addition...I would like to point out that hand usage is not always a bad thing, especially for you larger guys. A hand used correctly can extend the capacity of the mouth and continue the erotic suction that is so often desired. A hand with suction? Yup. The right lubrication (uh...remember that DT spit) and positioning can allow the hand to retain the suction generated by the mouth. Don't fault a girl for using hands...she may just give you the ride of a lifetime. Plus...it also allows for a little throat R&R....
For those of you who have missed me....I am UTR for a bit due to the final weeks of my current set of classes....yay.....finals.