Hello Randy,
I have implemented NetApp + XenServer since version 5.0 and now 6.0.2, I always recommend NFS over the Storage Link functionality (BTW, it is EOL by Citrix), what Storage Link do is basically to take your whole aggregate and create several volumes and creates as much LUNs as VM hard drives you have, that's ok if your filer is dedicated to XenServer, but not if you have a shared infraestructure, and since you are using iSCSI or FC you are tied to all the SAN disadvantages (and SL reported issues, take a look at Citrix's forums http://forums.citrix.com/category.jspa?categoryID=172). With NFS you automatically get Thin Provisioning and you don't have to worry about the Storage Link limitations for Dedup.
NetApp makes your life easy with NFS, don't complicate it, hopefully we will get a SnapManager for XenServer some day
