To a certain extent, I must echo MB's comments; if you don't have experience with winter conditions, solo in the Smokies can be a rough introduction if the weather is sketchy. If you're locked into dates, you could see anything from low 30Fs and rain/sleet, to high teens with near whiteout conditions, or clear and windy with single-digit overnight lows. I've seen all these on the same 5 day trip.
As far as your gear list, I would also drop the windshield reflector. I would add a bivy and a small tarp. If you don't have snowshoes in a storm, these can be lifesavers. I've been caught between shelters on the AT before in winter; a tarp and bivy are the difference between a forced bivouac and an emergency. The bivy will also be handy in the shelter, as they can be drafty depending on wind direction.
On the clothing front, make sure your feet stay dry/warm. Extra socks, tall gaiters, waterproof socks, neoprene for stream crossings, all are essential. Also spare glove liners, and waterproof shell mitts. I like a waterproof wide-brimmed hat like an OR Seattle Sombrero in winter; I can wear a windshirt with the hood underneath the hat and be relatively protected from snow.
Rather than add a synthetic puffy, I would add a fleece pullover/hoody. Fleece is great in variable conditions, and will prove invaluable if daytime temps drop. A Powerstretch facemask weighs one ounce and combined with your beanie and buff under a good hood would be sufficient for the worst weather possible in the Smokies.