Let's talk about throughput. SATA RAID rebuild times are now unacceptable, and flash isn't the answer.
The obvious answer was once to put more arms and heads in the drive. No-one did that because RAID came along and and you could stripe IO across many heads for cheap.
That does not work when you're rebuilding a bad disk.
The Winchester disk guys (and RAID controller guys) can build a dual-arm SATA drive, doubling throughput, that's competitive with flash on unit price. Discuss.