Has anyone done any data migrations from an IBM XIV g3 to Vmax?

gem_guy,

You can do it through VPlex Migration, but you need to keep in consideration the IBM XIV's work on Decimal counting where as EMC uses Binary for sizing.

If your hosts have powerpath, you can use ppme to do host based migrations. If not, you can use Open Replicator hot pull which is a lot like the XIV migration utility. Zone the FA ports your hosts see luns down to the XIV and use unisphere or SYMCLI to create and execute the migration. A simple host zoning change and reboot and you can access the luns on the VMAX. There are good white papers regarding this on the support site.