I've tried moving a Plesk 8.6 installation on SuSE 10.0 to a Plesk 8.6 installation on SuSE 10.3, but this doesn't work (see https://kis.hosteurope.de/support/faq/index.php?cpid=13913 (requires login)).
Downgrading to openssh-4.1p1-10 allows Plesk Migration Manager to work, and to avoid opening up vulnerabilities I've used...
/etc/hosts.deny:
sshd : ALL : DENY
and
/etc/hosts.allow:
sshd : xxx.xxx.xxx.xxx : ALLOW
... to limit ssh access to the new host's IP address only.