It's late and your list is a bit overwelming for me right now, but you have done a thoughtful job.
As an AT section hiker with only 300 miles in VA left, here is what jumps out at me.
A 2 pound tent, even though it is a fine product from Henry Shires, will start to feel heavy when you know there are much lighter options available. Start with Ron Bell's site at Mountain Laurel Designs...NB he responded to your post and yet, never even put in a plug for his shelters, so I will.
I, too, started thinking I would avoid shelters, and I did. Then I started staying near shelters, but not in them. Then I started using them more and more. Not only did I enjoy the company, but the convenience, too. No need to fumble around in the rain with a tent or tarp. A nice place to organize gear. Saves time in the morning.
Suddenly when you start using shelters, you begin to wonder why you are lugging a two pound shelter.
But, sometimes shelters are full, or you recognize that hiker who snores, or you want to hike a distance beyond the neaerest shelter, having your own shelter is a must. Somewhere there were two shelters at one site and one had a sign that read "snore-free shelter"!
(Once in ME, I could not reach a shelter because I did not want to cross a swollen stream) Think tarp. A two person tarp gives you plenty of room at a weight less than a one person tent. Worried about mosquito season? A SMD Wild Oasis weighs 11 oz.
A tarp can be tied-off between two trees, don't even need your poles every time.
(I have used a tarp hung over me in a hammock skin which I do not have to unpack unless it starts to rain!)
Packs: I have used lots of frameless, but when out for two weeks (JMT), I was really missing a chance to the get weight off my shoulders. A variety of Granite Gear choices fit me well with the light, but effective frames ( eg. Vapor Trail)(Osprey packs are very popular, too, along with ULA and the long stand-by farmes of the Gregory's.) So far, I only remember seeing grey haired guys using Kelty exterior frames from the good ole days.
Keep in mind the cuben fiber pack and shelter options from Zpacks, I see you have a stuff sack from there.
A light with a strong spotlight option works best for me when looking for AT blazes at a distance in the dark. (see Ron Bell's comments) The dimmer lighter options do not work for my eyesight any more except around camp. The popular brands of headlamps have both options in one light.
When using just sticks for waste holes, the holes I dig usually do not get deep enough. Using a winter stake or small non-plastic potty shovel (eg.ProliteGear) really do a better job of it, especially among the roots and rocks. I use shelter latreens a lot even if just passing by. ( Some are only a few yards off the trail.)Many are odor-free composting out-houses with nice views and a door you can kick shut if another hiker comes along.)
You really do have a good list and the advantage of the AT is that it is not too hard to revise as you go. There are many post offices and outfitters along the trail,too. (Walasi, GA, Gatlinburg, one near the Fontana Dam, Standing Indian just outside the northern boundry of the GSNP, Hot Springs, NC (or is it TN?) Damascus,VA, at least one in MD, and Harpers Ferry, Duncannon PA, Port Clyde, PA (Cabella's not far off trail in PA), Delaware Gap, etc...All see thru-hikers everyday!