What!? That's completely the opposite to my experience! Essentially, after setting up ZNC to your liking, all you have to do in your client is change the irc server from say, irc.freenode.net to znc.yourserver.com:port and add a password for the server, username/freenode:password, done!
I thought it'd be annoying having to add servers through the ZNC interface (either web or SSH) but it automatically adds/removes them when you join/leave.
In terms of buffers, I generally don't have it set to 2000+, normally around 100 max. I'll just go through the logs if I really need to catch up.