I am in 6b by most of the maps. You know the Extension Service planting map has us the same as northern MO. This is supposed to account for elevation. It shows northern MO in a colder zone. Your article mentioned microclimates. When I used to drive 26 miles to work and it snowed, some areas would have snow sticking and some would be obviously warmer. Also riding a dune buggy years ago you could feel it was warmer on the top of the hills. My valley is a frost pocket. I may really be a zone colder.

Here is a link that might be useful: a link to the same as above