Question: I assume that an Endpoint is one business that I am serving, rather than the number of people that may be on their server - true? Given that the number of clients that I can fit on one server is limited (by diskspace), will the client license extend over multiple servers until my limit is reached or is this a single server license? If I am using multiple servers, do you have software for connecting these servers so they act as one virtual server, or is there some other way to handle this?
Answer: An Endpoint is defined as one account on your RBS Server - a single installation of the Endpoint software. In many cases you can back up all the computers at one company using one account. If you're backing up one file server at a company, that's usually one account. Sometimes companies want multiple accounts so they can keep backups separated by departments.
The number of Endpoints you can fit on one RBS Server is limited by disk space and bandwidth, mainly. You can easily scale both up as big as you need to handle hundreds of Endpoint on a single RBS Server. And that's what you'd do, rather than installing several servers.