First, let me say, this is a great time of year to hike the LT! The leaves may just begin to start changing and there just aren't that many people out right now, except at the major day hiking spots (Camels Hump, Mansfield, Ab, etc).Have you done the LT before?
I think you're right to focus on drops vs. filter, phonco/tarp vs. Tarp/shells/cover, and Aircore vs. Closed-cell.
I've been out on the LT trail in three different areas this Sept in the Linoln, Duxbury, and Belvidere areas. It's not "wet" out there, but it's not dry either. I just brought two 1L Polar seltzer water bottles and chemical drops as I was fine. I would think that the ridge by Sugerbush would be the only real dry spot, but you should be fine if you fill up at the pond by the Ap Gap. A filter won't help you there anyway, since there just aren't any sources period. With a 3L platy you'll have plenty of water, just bring a small scoop.
Next, as you brought up, I'd suggest that you ditch the tarp, shells, and pack cover. I'd just bring the Golite poncho/tarp. In fact, that's exactly what I bring with me. My dog and I camped out under my poncho/tarp this week on the LT by Bamforth Ridge. Honestly, from what I've seen, most Thru hikers go from shelter to shelter, because good camping spots aren't always easy to find on the LT.
Finally, if I were you, I'd ditch the Aircore for the Z-rest. Maybe it's just me, but I find the air mattresses to be a PITA. I find that it's quicker and easier to unpack and pack the Z-rest in shelters and it doubles as a camp chair.
Anyway, I'm not much for looking at gear lists, but I figured I'd comment on the points you brought up. As I mentioned before, I think that this is the perfect time to hike the LT, so you should have a great time.