For a little clarification. In March I used a nonbreathable cuben jacket that I made and it also served as a vapor barrier. This worked well but quickly became too hot and forced me to switch to the WPB ones that Zpacks sells. I would have made my own but I was already hiking. Another member offered me a great price on the pants and jacket and got them to me on the trail.
The Zpacks jacket breathed well enough for me. I really like the fit and hood. I had high hopes for the jacket but could never keep the water from running down my neck and soaking me out. In light rain this was not a problem but on the AT rain is often not light. I think when I have to replace the jacket I will make my own and attempt to make modifications to get a little better coverage. I do like the material a lot. I think that the pit zips would be a good addition but once added you are creeping up into the wright range of some other jackets that are much cheaper.
The pants are amazing. I am pretty sure I will be using WPB cuben rain pants until the invention of a better material. I liked having them to wear while doing laundry and used them for warmth once I traded my hiking pants for shorts. Here is a pair on gear swap.
Another thing I used was WPB cuben rain mitts. I made these myself. You can see a pair hear which I had leftover and sold. They worked very well.
The hexamid worked great. I hiked as part of a couple and we used the Hexamid Twin. With UL gear we had plenty of room for all of our gear and ourselves. We used Torso length pads and would put our packs under our feet. They were often wet so we would turn our pack liners inside out then put the pack in there to keep them from getting use wet. We tented 90% of the time and there is still a lot of life left in the tent.
I also think having the separate ground cloth is very nice. It allows you to have some protection for your pad when you are staying in the shelter. Also the shelters are very dirty and it will help keep your pad and bag clean.
We used MLD Prophets for our packs. We thought they were the perfect size and performed very nicely. I have picked up a Zpacks Arc blast for the pct though because I want to be able to carry more weight and more voulume (food). I dont't think I would take a pack this large on the AT though and often found the prophet too large. I would suggest buying your pack last in order to determine the size after you have the rest of your kit together.
With all that said. You could take the list you have and be very happy. It is a great list and Would probably leave you at about 9 lbs. Anything less than 10 lbs is great for the AT. Though you might not realize it from reading this site but you might only see a dozen or so other people with base-weights in this neighborhood during your trip.
It's such a great trip! You are going to love it.