Removing virtualization can be highly disruptive to file servers and NAS platforms, but it really depends on what you're using virtualization for.
As an example, file aggregation can change the way that data is organized, so you may need to unload all of the data, remove the file virtualization layer and then reformat and reload all of your data from scratch. By comparison, data migration is one of the most transparent file virtualization functions. You can install the virtualization and move the data to a new location or storage system. Afterwards, you can remove the virtualization layer or turn virtualization off until it's needed again.
Replication falls somewhere in between these two extremes. If the virtualization layer is required to successfully access the replicated data, removing the file virtualization layer can prove very disruptive unless the replicated data is in a format that applications can work with. It's important to test "back-out" procedures to weigh the disruption involved and determine whether key data will be left stranded.
Go to the beginning of the File Virtualization FAQ Guide.