[c-nsp] Cisco VSS upgrade - time needed?

[Bernie]

Hello! I'm going to be performing my first upgrade of 2 Catalyst 6500
chassis to a VSS in a few weeks. There are only FastE and Supe modules
installed, so I'm thinking my outage window will only need to be 3-4 hours
(inc. rollback time for problems). Has anyone on the list done this
conversion and can you confirm my outage time estimate? On a related note,
what was your personal experience with the actual network outage time
during reboots?

Thanks!

Bernie