Was digging around the ReadyNAS community for the current state there. Seems it's still an issue even on the newer units running newer Netatalk releases. One person caught the new bit rot detection feature discovering an issue in the time machine files on the NAS. (ReadyNAS units running OS 6 use BTRFS). He's also being told some rather bad things by support, trying to cut him off at 3 months into a 3 year warranty.

That answers my own question on if it would be worth going through the pain to manually upgrade my units to OS 6. At least for this particular issue, it wouldn't be. And the warranty issue that user exposed sadly confirms the downfall of the ReadyNAS group at Netgear. While I used to support and push their products, I can't do so for this thread or for future NAS discussions.