I discovered a different issue. I had smooth stems on my Specialized Roubaix and decided to balance the front wheel one day to minimize vibration on fast descents. It required a surprising amount of solder wrapped on spokes opposite the valve stem. Then I got a flat and the only tube I had on hand had a threaded stem and "washer" (I'd call it a nut). Mounted it all up and found that the wheel balanced perfectly without any weight on the opposite side. Appears the rim was built specifically to balance a threaded stem + nut. Otherwise I'd go with smooth just because it's easier to put on the pump head. No weight saving if I need to add weight to make the wheel balance...