Not directly this problem, but using multiple SSL Gateways with different version, I had real problems with network connect the moment I upgraded one site to 8.1. The Tunnel to 8.1 was not working very stabile, beside some realy ugly installation trouble because, as it seems, the juniper services did not survive the upgrade. So a full uninstall with reboot was needed before the installation of the 8.1 network connect succeeded.
Haven't tried to upgrade any production site since then.
