We've got several OES (SP2) servers, all with LUM installed and
apparently working - I can LUM-enable a user, and FTP or SSH into the
servers. However, the home directory setting isn't working - by
default, I end up in /home/username, even though I've specified I'd
like the home directory to be set somewhere else.

For example, I've LUM'd the account "jbloggs"

oes:/~ # namuserlist JBloggs

From iManager, I go into the user account and change the home
directory to /bin, and this appears to be reflected on the server:

oes:/~ # namuserlist JBloggs

Yet if I FTP or SSH to the server as the user, I still end up in
/home/JBloggs. There's no errors in /var/log/messages or any of the
nam logs.

Can anyone suggest what's wrong?

I'm trying a new usenet client for Mac, Nemo OS X.
You can download it at http://www.malcom-mac.com/nemo