Simply ask the girls what they prefer, seesawing or a calm upper body!
But they are not wobbling around - maybe because I start almost every milonga with a qualified dance therapist that might perform some subliminal calibrations at the level of heart chakra and awareness.
When I told my tango teacher that I don't keep my shoulders calm but perform CBM, he was immediately in front of me for an assessment. I got no complaint, we had been talking different about the same matter. CMB is a natural part of stretching the axis from the supporting foot (behind) to the rib cage (a bit in front). The center (for me the solar plexus) has to keep calm on the path. That limits the amplitude substantially.