Just after some stats on how other companies balance their server manager session load. For comparison sake we're running TC 10.1.3.1, Windows Server 2012 and TC 4 tier clients for the users.
We currently have around 1700 user and have our load split across 4x Pool server with a server max of 500 sessions to accomodate some failover is we lost a server.
We're going to getting a few hundred more users over the next 12 months and are discussing the difference in upping the resources for the existing servers to allow more user sessions since we don't see our existing volume using more than 60% of resources on average.
The alternative is an additional pool server which will incur additional licence costs as well as be an extra box to account for when doing config upgrades, patch installs and any other admin tasks.