It's entirely up to you.   R50 is still supported by Dell.   With drives, especially SATA getting larger and larger, rebuild times are getting longer.   So the risk of a double drive fault becomes greater.  RAID6 greatly mitigates that risk.     What are you backup and DR strategies?   What would happen to your business if the array faulted?  The revised policy is there to help you make such decisions.  Help you find the balance that's appropriate for your situation.   EMC has stated the same thing about RAID6.   Regards, 
We got an email fom Dell, that raid 50 is no longer pest practice for arrays with 1 TB SATA an NL-SAS drives. Would you convert existing arrays to raid 6 or leave them running raid 50?   michael
RAID6