The autoformer/ct choke also leaves only 1/4 of the end-to-end inductance, instead of 1/2 the end-to-end inductance one gets when driving it balanced, in pure grid choke form. It's the same effect as a Class A v. Class AB OPTx load.

Interleaving also increases the Cw...and I'd prefer to have that as low as is achievable, given the other design requirements. On the capacitive load, the better sonics of the cascode MOSFET CCS is largely due to reducing the shunt capacitance( IMO ), and reducing the Cw of a choke is going to contribute in the same direction. Capacitive loads sound screwey to me, hence the interest in the Cw measurments of the inductive loads. Which gives me another thing to try when I get those interleaved phase splitter chokes in my hands and on the measurement bench...more later when I have developed the idea a bit further.
cheers,
Douglas