Would it be beneficial to tracking accuracy to wear contrast (to the room) body suit, where left/right side are also contrast to each other?

Different colors of left/right are not supported with our actor's model. You can improve tracking by wearing different colors on arms and torso (e.g. t-shirt over long-sleeve shirt), because these body parts often overlap.

Aye, thanks for the hint. Would it make any difference at all wearing tight clothes vs regular ones?

You can use any clothes you can adjust the model in Mocap Studio to. As you might see, the model pants look closer to regular fit than slim. Upper part may be shirt, T-shirt, pullover.
So regular look is preferred, not very tight and not loose. However, some users actually use tight body suits, and this also seems to work well.