If you apply for permanent residence, than yes, you have to provide your biometrics. However, if you have given your biometrics for visitors visa, you don't have to. Tricky I guess?
I tried under both previous PR application and under visitor's visa. In both cases, the answer was you must give new biometrics. (The text I quoted was from the visitor's visa version).
So the answer seems unambiguous - you must give biometrics, period.
And in this respect at least, the government resources are giving clear, simple, and correct answers.