Separating online redo logs from database files

Hello, listers

What are general pros and cons on separating redo logs from database files? 
Both database and redologs are already residing on RAID1 volumes. So this 
separation would only mean - move redo logs to separate mount point (RAID1, 
still).

We have EMC consultant insisting that it is in line with best practices. Why 
exactly is it a good thing, what "best practice" actually means - he can't say.

Our systems are moderately used OLTP databases. I we had lots of waits on redo 
log writes (and we don't), I would understand moving redo logs to flash drives 
(for example). Or, as I have seen previously, database goes to RAID5 and redo 
logs to RAID1 - depends a lot on database usage, etc. etc.

Actual real life inputs are welcome.

Regards,
Vladimir Barac

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