Some background:

A customer has asked an Certified SQL Server Consultant for his opinion on migrating from sql server 2005 to sql server 2008.

One of his most important recommendations was *not* to use backup/restore but instead use the migration wizard to copy all the data into a new database.

He said that this would ensure that the inner structure of the database would be in an SQL 2008 format, and would ultimately result in better performance.

The Customer is skeptical about this because they cant find any writing, in white papers or otherwise to corroborate the consultants statement.

So they posed me this question: 

Given an SQL Database, which originally started out on SQL Server 2000, and has migrated to newer versions of SQL Server using backup/restore. (and finally being on SQL Server 2005)

Would migrating to SQL Server 2008 using the Migration Wizard, and in effect copying all the raw data into a new database, result in better performance characteristics. Then if they would be using the Backup/Restore method again?