BIG NUT
Edit: I will say that even though the majority of the configurations were of the brass inner weight, the PC inner weight does increase the "roomy"/"booming" sound that James was going for, much more than the brass internal weight.
I think you can compare the differences between the config or the internal PC and internal brass portions of the sound test and come to that conclusion yourselves, however!
And for those that want a variation of sound test that sticks with one mic before switching versus the one above that stays with one config, but switches mics, feel free to check this out. And the review video of the proto units (keep on mind that since it was a proto run, there are design changes with those units versus these IC units).
For example, no PC plate, so those recordings don't really apply to this public run (and no top mount or course, but imo, not a huge loss at all since the board seems to really be tuned for gasket mount).
Mic Method Sound Test Compilation:
YouTube Video Review (Proto unit, so there have been changes):