8.0.x was just recently released. It offers a number of new features compared to 7.x. VMware VVOLs, compression for snapshots (on specific model arrays), borrowing free space for both snapshots, and replication. Delegated space for replication can now be in multiple pools, support for the new 6610 model array, etc...
So if you want or need any of those features by all means upgrade It is entirely up to you. Later on it will become the recommended release.
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