I'd like to read about how that goes! This is exactly what I want as well. I hear synapse requires a good amount of resources
Disroot's announcement was before the switch.
The team even talked about it with one of the devs in the latest Matrix Live: https://www.youtube.com/watch?v=Ad3oqEo5leM
It's pretty great. (Not just for mattermost, but most major chat plaforms)