Thanks for the advice.
We have arrived safely back in Kunming. After much deliberation we took the Songpan - Wenchuan - Dujiangyan route to Chengdu 3 days ago, then we drove to Zhaotong 2 days ago, then yesterday we drove from Zhaotong back to Kunming.
We decided to take the Dujiangyan option after much deliberation. We favored the relatively equal danger of taking that road over one day with taking a Northern route (all the way back up through Lanzhou - Xi'an - Chengdu) through an earthquake zone for 3-4 days. In Songpan we spoke with whoever we could find. A caravan of drivers from Chengdu who had come through there the day before said there was no problem, no rockfall, and that it was safe.
So... we made it through without a problem. Part of that was due to the weather, which was thankfully just overcast. Having now driven it though, I would say it's still too dangerous and would not take it again. I'll explain below.
It is definitely a gorgeous drive. If it weren't so prone to disaster I would have taken it more slowly.
Between Wenchuan and Dujiangyan North- and Southbound traffic is being alternated on a schedule that no one seems to know about. We got there at 1pm (there were about 100 cars in front of us) and sat there for 2 hours before they let us through. Once you can go, traffic stays mostly on the Southbound side but gets redirected (rather informally) to the Northbound side 3 or 4 times. This whole section is 80% tunnels. Really really long tunnels that all seem to be 2000m-8000m long. I have never been in such long tunnels. Some of the tunnels have evidence of water/silt collecting from the flooding, but they are generally new, clean and safe looking.
We saw some of the severe damage to the Northbound side of the highway. In several cases when the road hugged the mountain there was mud/rockfall that had blocked the road and has since been cleared. In one case when the river switches over from one side of the valley to the other the Southbound bridge that passes over it was completely wiped away. The pillars must have given out. Frightening. In two other cases rockfall destroyed part of the tunnel entrances. The old road, which wrapped the mountainside and seemed to have few tunnels, was completely destroyed in a few cases. The mountains here are tall and steep so when there is rockfall it comes through a ravine and then destroys anything in its way on the way down.
After Dujiangyan you're out of the mountains and are totally fine. Before the last (older) tunnel a group of police hands you a toll card since you're now in the clear. Otherwise there is no one directing, managing or overseeing anything. Random cars and sometimes police escorts still come through from the other direction while you're driving right toward them.
The drive from Yibin to Zhaotong sucks. The road is shitty and there were tons of places where recent land/rockslides had been cleared. We would definitely have taken a longer route back if we knew how bad it was, but it is so hard to find good information on current road conditions.
Anyway we are back in Kunming safely!