May I suggest RackShack change the verbage on http://www.rackshack.net/migration.asp to more closely match the actual downtime experienced by people for the migration.
I know you have to move, and it's hard, but accurate information is all I ask for.
I was down for what appears to be about 5 hours last night. I don't find it un-acceptable, but it was not the 90 minutes of downtime you told me to expect.