Ontrack's site says the software should only be used when hardware is functioning properly, not if it's failing.
Correct me if I'm wrong, but if a drive is failing, why would you have any use for recovery software?
especially if your drives are failing. if you don't have anything valuable on there then by all means (don't know why you'd need to recover it then), however 9 out 10 people would prefer some data restored over no data restored.
you'll be surprised with what r-studio can do. it even works with broken arrays.