RAID arrays is one of our specialities. Sometimes it is very hard to get data from such devices, but we have been educated in the well known USA company datarecovery.com for RAID recoveries.
It is enough to say that we recovered data from a cluster RAID-array for a huge IT-company. Such case can prove: we can recover data from any RAID array if disks inside have at least some good surfaces.
Mostly we have in our practice the RAID massives from 4 - 6 disks, and the most frequent ones are RAID-0 or RAID-5. We are able to recover data as from massives with all drives working (controller failure) as far as with non-working drives.