First off, you are not actually doing what you are asking of me yourself.
Take these models for example...
The plots on the left the antennas are mounted 6 meters above moderate ground, the plots on the right the antennas are mounted 11 meters above moderate ground. All antennas are 5/8 wavelength antennas.
cmctest1 and cmctest2 (the green lines) are nothing but the 5/8 wavelength vertical elements. There are no radials, and no mast/feedline. They are essentially the optimal installation for said antennas, and can be seen as the goal to shoot for.
cmctest1b and cmctest2b (the red lines) are the same antennas with a mast that directly connects to the earth below. There are still no radials in play here. These models simulate what an Imax would do if put on top of a mast with no form of CMC control.
cmctest1c and cmctest2c (the blue lines) are the same as the "b" models except they include radials.
If your models that include radials are the bases for your comparison between CMC present and CMC choked antennas then your comparison is flawed from the start as radials are, in and of themselves, a very effective CMC choke.
As for your request, a comparison of gain from the model I posted above compared to itself with a choke added, in this case the choke is made up of simply adding four 1/4 wavelength horizontal radials.
The DB
