Doug,
We went through a migration from AIX to Linux, and followed the steps
John Schneider recommended in some cases. However, we also negotiated
with key customers and many of them agreed to let inactive files of
their clients expire on the AIX owned tape pools. We registered the
clients on the Linux server, but restorals were still available from
the AIX server so long as the client options file had a stanza for
both servers. This saved a huge amount of processing time for us.
Depending on your retention parameters, exporting inactive files may
take longer than letting them expire.

Best wishes,
Keith Arbogast
Indiana University