Tonearms: the lightest, the best ?

This is exactly the way to do this. Just make sure you use common sense.

What is light? What is heavy?

What is a low compliance. I do not favour these vague terms.

Have you read Ladegaard's 1977 paper? Splendid:

It tells me, that not compliance nor effective mass are important.

But the Hz's of the rf and the dB's of the resonance- peak decide if the tracking is safe.

But too light arms will suffer a too low resistance against elastic bending- or torsion- defornmation. So the most harmonious combination of skills of them all will win the game. And there are more unfluencing parameters than mass and compliance on their own.