A coreless motor has more losses, not less. That's because the field isn't focused as nicely. It's just that the losses aren't in the core but in the air.
Core losses by the way are typically a different kind of loss, they are eddy currents resulting from the fact that the stator laminates are not infinitely thin.
Core losses by the way are typically a different kind of loss, they are eddy currents resulting from the fact that the stator laminates are not infinitely thin.