Exchange 2010 Database Page Fragmentation Caused By Archive Solutions – James Carroll – Site Home – TechNet Blogs:

In Exchange 2003 and 2007, we recommended not using an archive solution that stubs messages. Some of the issues that we specifically call out in Technet are ones that have to do with performance and having too many items in a mailbox. In Exchange 2010 there is a bigger problem that crops up, one that outweighs having high item counts and poor performance.

Stubbing (eg Enterprise Vault) has always been a bad idea.. now even moreso!