That's been kind of the general consensus I think. That's why we're leaning pretty heavy towards riding the Blue Ridge unless something happens to change our minds.
What we have been discussing lately is what kind of weather swings we might expect to encounter in Sept? The closest we've been was one year we were in Gatlinburg and went over the mountain to Cherokee NC. It was very hot in Gatlinburg and as we went up and over the mountain it got much cooler, not cold but cooler. I am thinking that in the middle of Sept on the Blue Ridge we might expect over night temps in the 40's to be possible?
I looked at a few weather sites to check, and you seem to be on target with the lows, at least in the higher elevations. Planning for the unexpected is key as long as you have the room to pack what you may need.