This is a 10 cost break team. E0S1 Rappa, HMC on S5 DDD, E2S1 Dahlia and Fugue. Last patch this team zero cycled the first stage of Pure Fiction. Today, this team barely 40k'd. Neither last patch nor this patch have an especially break favorable buff.
Usually on endgame reset days, I spend extra time to try and optimize runs. I don't think it's worth it for this one.
HMC in Pure Fiction is kinda nutty.
The new Himeko Nova trailer gave me a new favorite. The transition is incredible! It's up there with the ending of Coronal Radiance for me.
My point is still that your sustain choice does not make a significant difference in clear time for Rappa and break in pure fiction unless you have Lingsha. Just because he is a break sustain does not mean that Gallagher is well suited to this team in this environment.
I saw no significant difference between running Huohuo and Gallagher this pure fiction. Also the lightning idol enemies suck. TLDR: if you don't have Lingsha just stick whatever sustain you're comfortable with on your break team if you can't do sustainless this refresh.