As you point out, the inductive reactance of a plate choke drops with frequency. So that normally you spec the unit (inductance wise) to deliver X amount of henries so that at your lowest freq of interest it is sufficiently large to do it's job (i.e., provide an impedance load for the anode to work into).

Once you have that pinned down (at your lowest freq of interest)... the impedance created by the inductive load increases with frequency and can become substantially large (much larger say than a chosen plate resistor value for a particular application).

I think you have all the basics down pat... including the disadvantage of a plate choke being far more expensive than either a CCS or a pure resistor load for the anode.

msl