Can't comment on Netapp but we use Avamar to backup our VM's with the avamar client running in the guest OS. The de-dup is amazing! The 1st production VM we backed up was our VC server. Avamar only backed up 57% of the data on the server and from that could reconstitute 100% of the data. Truly amazing! It's very pain free to use from an admin point of view also.
Cheers
Paul
