I’m not associated in any way with the Moobot’s staff, but i believe the best way to do something in large scale would be having multiples instances of the bot running in multiple servers.
For example, you can have 1 instance of your bot connected to ~30 rooms, then you can have 20 instances of your bot running in one server and have multiple other servers, with this kind of setup you can have your bot monitoring 600 channels with only ONE server.
Of course these values change with your server hardware, you may not be able to have 20 instances running at the same time, but that depends on how your bot was made and the kind of hardware your server is running.
Note that you can have as many instances of your bot running as you want in the same account.