OK, so what I've gathered so far from my research.
Parity Delay = never used with X-RAID2
Block Size = 64Kb (newer units default) 16Kb (some older units default) although neither seems correct in this case.
Parity Rotation = Left Sync.
This job is just taking forever because it was reconfigured and I'm having to scan about 20Gb each time I try a new setting to see the results. Getting really bored of it.