As much as I'd like to say that Red Gate is the way to go, I think you'd be better off using SSIS to build out a migration between the two. The Red Gate tools for moving data around are good at what they do, but they won't be able to generate new key values and apply those new values to related tables. You can do that much easier through SSIS.
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Author of:
SQL Server Execution Plans
SQL Server Query Performance Tuning