"A decade or so ago, the high street bank I worked for was supporting around 30,000 Notes users on just a single clustered pair of AS/400's (in the UK, others elsewhere). With failover to another pair at a recovery site. I personally built the first server in the domain and was the first user registered."
Voted up for being willing to put your name on the post.
I get the feeling Lotus/IBM should have enforced a bit more consistency, but how to do that while being backwards compatibility is going to be tricky.