I was excited to roll it out at the Linux Foundation. We are no longer rolling out new instances and Hyperledger[0] is looking for a replacement due to an issue[1][2].
It has been fine for our use case. We have a few hundred users on it, but we only use it over our corporate network. We're running it in kubernetes and it scales up and down as needed.
[0] https://chat.hyperledger.org/
[1] https://github.com/RocketChat/Rocket.Chat/issues/15583
[2] https://github.com/RocketChat/Rocket.Chat/issues/15391