What's the nature of the broker in template 2? Is it just the broker application being scaled here, or the backend components too? If just the broker app, are the backend components off on some supporting host?

It sounds like you want to have all of the brokers able to do capacity monitoring and emit events. I guess for simplicity I always envisioned just one broker at a time running the node-manager service. I guess it's not really that hard to make every broker do it and just coordinate via DB locks, but it seems unnecessarily complicated.