A star nut isn't the best of both worlds...an expanding wedge is, and i don't mean a quill style wedge.
The types used for carbon steerers make the most sense as they expand evenly all the way round unlike a stem style wedge quill, but they also allow tensioning against the base of the fork like a star nut whilst still allowing complete removal without resorting to hammers and scoring the inside of the steerer.
A star nut isn't the best of both worlds...an expanding wedge is, and i don't mean a quill style wedge.
The types used for carbon steerers make the most sense as they expand evenly all the way round unlike a stem style wedge quill, but they also allow tensioning against the base of the fork like a star nut whilst still allowing complete removal without resorting to hammers and scoring the inside of the steerer.