Just a quick test of copying a BD Rip from one share to “Public,” I’m getting about 16 MBytes/second, and the Samba threads (two of them, of course) were pegging the CPU to about 80% while the software RAID process was about 20%.
I’m config’d with RAID5, so all 4 disks are thrashing like mad when doing that, trying to do a large simultaneous read and write 
Doing Share-to-Client, I’m getting about 60MBytes / second.
With a box like this, you have to make sure you’re comparing similar setups. If you’re doing RAID, and they’re doing JBOD, the numbers will be quite different.
Another example: Copying from Volume_1 to Volume_2 that reside on different disks will (usually) be faster than copying from / to different shares on the same volume.
