I'd echo Scott's comment re: colder temperatures in the hills. Also be prepared for the possibility of significant snow on the ground.
I've not hit the stretch from Allen Gap south yet, but hope to in the next month or two. However, I went from Sam's Gap (~3700') to Allen Gap on Jan 15-17 (a couple of short days there), and spent the last couple of weekends on Roan Mtn (~5500'). Both are a bit north and a bit higher, so represent more extreme possibilities
I live in the Tri-Cities area (~1600'), about 30 miles north of Sam's Gap, and drive over Sam's Gap several times each week. Temps at the gap are typically 7-8 deg F colder than at my elevation. Roan, with its higher elevation, often sports temps some 17 deg F colder than in the valley
Your gear list doesn't look bad if you run warm and are careful to stay dry; I might want a warmer bottom layer at night and perhaps high gaiters. This weekend's forecast could include rain, so keep the down dry; if I use a down bag here, I usually bring synthetic insulative clothing.
My Jan 15-17 hike began on bare ground. Within an hour, I was perhaps ankle deep in snow. An hour later I was punching size 11, mid-calf post holes (no snowshoes on that trip). The deepest snow was of course on the northern side of the ridges, fairly protected from the sun. In one stretch I slogged 1.5 miles in snow up to knee deep. Kinda slow going there. Temps were reasonable, with a low around 25 and highs 35-45.
We've had a lot of snow since then.
You might also budget time for "is this the trail?" moments. The Sam's to Allen stretch is crisscrossed with various trails. Sometimes blazes are few and far between, and the correct path may not be immediately obvious in the snow. I spent some time on "a" trail, but not "the" trail, resulting in a bit of backtracking.
Roan was way colder. Igt currently has several feet of wonderfully powdery snow in the woods, with some drifts hip deep.
I hit that with snowshoes and skis last weekend, and still sank mid-calf sometimes. Lots of snow-laden, overhanging branches.
Tracks completely disappeared overnight or quicker, it was challenging to locate 2x6 white blazes on trees covered with snow and ice, and snow depth sometimes put the blazes at hip height rather than head height.
I spent a fairly comfy 5 deg night in my Phantom 32 bag, supplemented with every article of clothing I had along.
=> (top) Cap 2 zip-t, Stephenson's VBL shirt, R1 hoodie, MB UL 1/2 sleeve down jacket, Pat Puff Pullover
=> (bottom) UA Boxerjock, Cap 1 bottoms, Stephenson's VBL pants, BPL Cocoon side zips
=> (feet) poly liners, VBL socks, wool socks, ID HotSocks
=> (head) MHW windproof fleece hat, R1 hood, BMW Cocoon Pro 90 balaclava
=> (pad) TR Prolite XS, TR Ridgerest (tapered, 60"), blue foam sitpad under torso, empty pack under legs
=> (bag) MHW Phantom 32. Total loft measures about 3".
=> (bivy) MYOG Sil/Momentum
=> (etc) around 1 or 2 AM I added the MSR Twin Peaks as a blanket -- slept soundly then until 0730
Up on the bald I found a layer of powder, then thick ice crust, then more powder, then more ice.
As I said, this is probably more extreme than you'll find, but do be prepared for temps about 10 deg colder than the forecast, and for the possibility of some deepish snow on the trails. Should be an excellent trip -- enjoy!