I have had a moan about this before,
one specialist running shop said "I was a severe over pronator" and sold me NB854, I got injured,
went to another specialist running shop and he says that "I only over pronate slightly on my right foot, the left is neutral" and he sold me Nike Air Span Triax, so far I have done about 250 miles in them and they seem ok apart from that I get blisters on my right foot.
So who is telling the truth and do I have to go to another shop and get told a different story again and get sold more shoes............