I never used Exchange on Netapp, but aren't they supposed to have a "SnapManager for.." tool to coordinate the Exchange backups with the storage snapshot process? I was using it for SQL Server.
you can have whatever redundancy you want, and maybe even lagged copies, but if you need to restore something months older, you still need backups..
Exchange does not needs NetApp HA capabilities if you use multiple copies of database.
In our case NetApp sold snap manager for 30 remote copies of already triple redundant (one remote copy) database and then tape backup at month end.
In my view they just fooled the unsuspecting customer and just oversold everything.
That was fine too if it would have worked.