Perhaps i should have clarified. In all cases , there will be a change of ride quality because the suspension independence is lowered. IE, if you left rear wheel goes over a bump, your right wheel will be affected moreso with a heavier swaybar.
However in many cases, it may be so minimal that it is not noticeable. That said, when I fitted a heavier swaybar I did notice a difference in ride quality, but the handling was significantly better with the heavier bar.