Kit shows a lot of thoughtfulness RoamingGnome. I like it.
Couple thoughts and questions.
1) planning on using the 20* ZP bag/quilt the whole time?
2) suppose you're switching out the 13+ oz Gander Mt convertibles for something like 5 -6 oz nylon running shorts around last wk of April-early May? This has the potential to save 7- 8+ oz.
3) As Carl said resupplying more often has the potential to drop some significant POUNDS carried never mind ounces. Since it seems you are willing to switch out gear and buy gear to save wt perhaps, as it turns into fairer weather, you can also go to a lesser volume lighter wt pack commensurate with lower wt and lower volume food hauls and less voluminous heavier wt colder apparel? A Zpacks 60 L CF hauler may not have to be the end of line in saving backpack gear wt? With your kit one of the more bulkier categories of items can very well be food. If you reduce food volume, however you do that, I think that can get you to the tipping point of evolving or switching out to a lower volume and hopefully(that's the goal) lower wt backpack. Might be something to consider especially since I'm seeing a knee brace in your gear list.
Just a word. Might work your way into your hike if you have knee issues or don't want to aggravate anything existing. i.e.; don't got out the gate too fast too hard too big. HYOH. You do your hike not someone else's. If I can do it still treating a broken ankle you can do it. Be mindful of that as your approach entails minimizing in town time/more time on trail. FWIW, being on trail around other thru-hikers so much it's easy, VERY EASY, to be tempted into doing miles and miles and miles or doing what others are doing when possibly you could be/should be doing what's best for you concerning your body!
4) with your start date good chance(I'd count on it!) you'll encounter times walking in snow. Do you have at least one pr higher height calf height socks and/or something more WR or WP gaiters than the DGs for those times. DG's are great for summer or when it's dry to keep debris out but untreated lycra DGs quickly wet out despite the low wt. Perhaps, treating them with a spray on WPer like ReviveX or Grangers could help since you'll be wearing pants but even still expect wet possibly cold feet and possibly ice up around your pant cuffs and low cut trail runners. Consider more protective shortie gaiters like made from eVent or Neoshell or Schoeller for using the first 5 or so wks. Then, if you like to use gaiters switch to UNTREATED DG's for summer. For me, IMHO DG's aren't a necessity for the mid Atlantic states even with the low cut Solomon's. To each their gaiter own though.
5) I suppose one of the reasons you're choosing to rock the Speedcross 3 is for their very good traction which will be appreciated with your start date conditions that can or WILL involve snow, ice, mud, and slush. I don't know if they're offered in a WP version or if you have the WP version. I assume you aren't taking the WP footwear path. Although that may not be a bad choice for your first pr for the early phase of the thru and then switching to non WP version on your second pr as it gets warmer. I suggest you consider treating that first pr whether WP version or not with ReviveX or Grangers. This helps in several ways and during those cold/cooler periods doesn't have to be such a big deal regarding shoe dry times or breathability compared to warmer months. Applying this WP, DWR, or silicone treatment can help to reduce ice/slush/mud/water build up on the upper and around the gaiters which this combination can have a tendency to do. Don't treat the very bottom of the soles as this can temporarily reduce traction making for slippery footing. Uppers on the Speedcross can hold water, snow and ice and possibly affect the speed lacing system. This makes the lacing more slippery too.
6) with the low cuts and your late winter/very early spring start date you'd be wise IMO to carefully consider everything going on with your feet as a system- a layered integrated system. Sock choices should be carefully considered. Two obvious priorities stand out a) warmth, especially for those first 5 wks or so b) taking care of your feet throughout the hike recognizing how that might change in the cold compared to late April/May on. I guess you've considered one pr calf height socks in that two pr scenario for the beginning during hiking in snow/slush? Here's something you may consider: take two pr of different socks for versatility to address varied weather during at least the first 5 wks or so. With the non WP Speedcross one possible scenario might be to take one pr of merino socks of your choosing the other pr being something like a
Hanz insulated WP calf height sock breathable and stretchy. This way you have versatility and address warmth while not having to have wet feet as much. It's an approach that has worked for me nicely in cold shoulder season temps rocking low cut trail runners and light hikers 1/2 size larger. As weather warms you can switch out for two pr ankle height socks. This sock scenario has the potential for you to possible eliminate 1 or both pr of the liner socks. You're call but seems a bit redundant in what amounts to carrying 4 pr of socks IMO with two pr liner socks and 2 other pr. To digress liners socks are possibly useful but once feet become toughened to LD hiking, with modern advanced sock design, and knowing how to tend to and treat feet PREVENTIVELY they can be less useful. You may only need 1 pr. Where they possibly have greater potential IMO is before feet become toughened and/or warm/hot LD starting times.
This shows wherewithal, a willingness to observe and adapt and develop, "I'm sure our packs will change many times during those 2189 miles."