Originally Posted by Retro Grouch
Depends on the individual wheels. Some 3 spoke in the past, for example, have had roundness problems. I'd imagine that a cast metal wheel would have a serious weight penalty compared to a wire spoked wheel.
There are 6-spoke wheels that are lighter than the lightest traditional spoked wheel. But I have no idea about their roundness. I would guess that, given precise casting and subsequent machining, their geometry could be made within the same tolerances as a well-trued traditional wheel.