so the main reason not to use a red over a green in single drive storage is the way it handles error correction right?
Presumably the Red has an adjustable ERC, as enterprise disks do, so you could ratchet it up so that it's in the realm of a Green. Otherwise, you could not want to use a Red in a non-RAID situation, with default ERC, because it will quickly just give up and start throwing sector read errors, which in a single disk situation will cause all kinds of mayhem.
is it possible to use western digitals tools to change the error correcting to that of a green drive?
I'm pretty sure the Red allows TLER adjustment (check the smartmontools man pages for scterc to find out).
You may very well want to do raise the TLER value (or disable it entirely) if one drive dies in RAID 1 and 5, or once a second drive dies in RAID 6. After the critical number of disks fail, any sector error translates into data loss, so more aggressive ERC at this point is more desirable.
People with mission critical situations, truly mission critical, will have a cluster file system with replicated storage bricks. So such a storage brick that starts going wonky, with lots of delays retrieving data, is going to be demoted out of the cluster until its array(s) are non-degraded.
also in raid1 is tler beneficial?
It depends. If you're using a RAID controller that will time out and eject a disk out of an array when a disk goes into deep recovery, then yes a WDC disk with TLER is beneficial in that the delay will be less, the controller will correct for the error instead of dropping the disk. However, once a disk is experiencing 7+ second recoveries for sectors, it's in trouble. Why isn't this disk being monitored by smartd? Why isn't this disk being periodically scrubbed? There are maintenance tasks that will help avoid this ridiculous TLER "problem".
And by the way it's ERC. TLER is a WDC marketing term for their version of it.