The whole thread comes down to one thing. Be prudent and be safe.
Mostly, what seems to me, that this thread is looking at, is “where is it on the trail that weather could cause me to fall down and end my thru hike.”
I would say ice in the Smokies because it almost took out my thru hike in '99. A set of mid-boot crampons that weigh all of 5oz could have gotten me safely thru the black ice without that bad fall that bruised my knee.
In the whites, I did have my winter clothes. Finally, I reached Katahdin before the end of September.
I am a klutz and can’t tell you how many times I fell down on the trail. But, in warm weather, the only thing I hurt was my pride. In the Smoky Mountains, though, I almost ruined my thru-hike because of lack of knowledge of how weather works in the higher zones of the Smokies.
Mr. Boo