There shouldn't be any issues with this set up
The issue with the ND7 servers and the
OOS are because as the router delivers the mail to the mail file, that
is when the service kicks in. The routers on the ND7 servers do not
know about the service, so if we failed over to a ND7 server, those
users with the OOS enabled would not have replies sent. There shouldn't
be any issues with using older clients using the agent though. The
Out of office goes through a series of checks to see what to enable, the
service or the agent. If we are enabling the OOO from a Notes client
prior to ND8.0 or in a mail file that based on a template that is
older than ND8, we will default to using the agent. Those users
that are on the correct versions of the client and mail template will get
the service.