We have not observed any real world advantages of using PVR-versions of HDD on Magic TV, compared to the usual desktop versions, when the HDD is not faulty. When the HDD becomes faulty, we do not see any advantage or more graceful behavior from it either.
The only difference between the Green and AV-GP would be firmware settings like those for head parking and enabling support for the ATA streaming command set.
If the PVR doesn't explicitly support ATA streaming then I don't think it will be enabled. The WD Green head parking occurs after 8 seconds idle and causes a modest delay as the heads must reactivate before the platter can be accessed.
ATA streaming isn't just about performance but system stability. With a desktop HDD the files' stability is placed above system stability. So when a desktop HDD hits a bad sector error and takes too long to recover from the error a PVR will lock up. With ATA streaming the normal error correction checking is disabled for transmission stream files as a few 0s and 1s swapped in a M2TS between the drive and the CPU doesn't matter.
RAID systems expect a drive to support TLER or time limited error recovery. So if the HDD doesn't have a TLER timeout of 7s and spends 8s trying to recover from an error it's marked as failed and thrown out of the array. All desktop drives which don't have TLER enabled are inevitably thrown out of a standard RAID array for this reason. A drive without ATA streaming enabled or a low enough TLER in a PVR will cause a system crash once it hits a big enough error.
I would still get a Seagate ST2000VM003 in preference to the AV-GP as it's 5900rpm. The Seagate Pipeline HD drives are rebranded Seagate Green drives with the ATA streaming command set included.
But it's odd that the error message is never encountered whilst using 3.18, and the programmes always record.
From the 3.18 firmware release notes:
"Fix a booking problem with specific regional channels"