I talked to LeFevre about this awhile ago. His call was that, though toroids look cool to people due to the optimized iron circuit configuration, they cannot be made to have fine resolution due to the severely compromized copper circuit config. The winding and interleaving lay is very screwed up by the huge circumference difference in the outside and inside of the core. On the inside, the windings are piling up; on the outside, the windings are spaced apart, and the next (interleaved) layer is falling into the spaces.
In practice, this appears to be true. There is an earlier product designed by Van der Veen, which I have not tried either. I haven't heard much about them.
Aloha,
Poinz
AudioTropic