Awesome link. Thanks!
Well, now I am doubting my conjecture about why there is reciprocity. It doesn't seem to have anything to do with educational requirements.
Vermont is wide open, no classes, anyone from any state that owns a gun can carry there. So, they allow the largest group of other states.
When clicking on Vermont here http://www.handgunlaw.us/, it appears that Vermont enjoys the largest area of reciprocity, also.