As the SteveN referred to in the OP, I would just like to point out two things:
1) As I went on to explain in the original thread, it is clear that Dawkins was referring in his book to symmetry with regard to the list itself (i.e. 100% theist to 100% atheist) - he was not implying some kind of symmetry with regard to the credibility of the two stances. Iano knows this but nevertheless started this thread to object to the latter (strawman) argument.
2) Although from a scientific sense, it is usual to accept that the non-existence of something cannot be disproven and one could therefore argue, as Iano does, that a '1' is logically more defensible than a '7 (albeit with little success it seems), given the evidence, a '6' is orders of magnitude more credible than a '1', '2'', '3' '4' or '5' IMHO.