The misleading ‘maxRadius’ property of these metaballs actually determines their resolution, and needs to be set to at least 10f to ensure a spherical shape. At the same time however, this property also affects their size. At a maxRadius of 15f, the metaball has a radius of 6f. This is considerably larger than the standard radii of my player bodies (0.5f), so I ended up needing to tweak a bunch of parameters to get the particles to begin behaving as they should on the metaball mesh SDF. It needs a lot more fine-tuning, but this is my progress:
Getting things right at this new scale will require additional adjustments that I did not have time for this morning (am super late to work). There also appears to be a small wobble in the SDF when I move the metaball around using the player. This wobble did not happen to the mesh when it was visible, so I probably need to adjust the SDF attraction settings.