When I did the trip in early September, I took a down sweater. This, along with light Icebreaker base layers was not enough. We got snowed on the second day.
We had friends bringing our resupply and joining us for the final stretch at Dollar Lake. While at Muir Trail Ranch we let them know to bring our heavy Icebreaker hoodies. It's tough to know right now what the weather will be like, but I'd definitely have a heavier puffy on backup next time. I was mostly cold in the evenings and at night. Mornings were also cold, but that quickly changed once we got moving. We rarely started hiking with the down sweaters, but they were on all evening and all night most nights. This was with WM Aspen 25 degree bags, Neo Air Large pads with GG Thinlight pads underneath, and a Lunar Duo.