I bought the 1TB Deskstar C revision recently at just $49 each and put them in RAID 1for my Desktop.
Look at how close the old Deskstar 1TB comes to matching the performance of the mor expensive Samsung and WD's?
This is phenomal, I can't believe the performance I've gotten out of these cheap drives.
http://www.tomshardware.com/reviews/hitachi-western-digital-terabyte,2017-6.html........
Why would you want to downgrade the superblock? Old mdadm verisons like mdadm 2.5.6 only use the 0.90 superblock/metadata and new versions use 1,1.0,1.1 and 1.2 superblocks by default.
There are some annoying caveats with this, first of all the new superblocks (later than 0.90) CANNOT be read by GRUB, so you won't even be able to install GRUB. Even worse, old versions of mdadm CANNOT automatically detect arrays even if they were created with a new version of mdadm with th........