I tried some of that stuff. I built a few versions, and helped another winder as well with his version. Jack has probably done a better job than MQ did. Tried them as phase splitters, in-circuit and on the bench. While the ones designed for phase spliting work well on the bench, they did not sound as good as a simple diff amp.
Such things do make good PP grid chokes. Leave teh CT split and you can do individual fixed bias.
regards,
Douglas