Or you could load up some rounds with and some without the LFCD and head to the range. Pretty simple actually. Unless you are afraid you will find out that this die actually does what Lee and thousands of handloaders say it does, Improves accuracy.
I know, I know, wasting my time and yours. You will never run an accuracy test for yourself. You have theory and speculation, that's all you need.
Or you could drive a couple of hours and start competiting in long range or mid range matches and find out that your conclusions based on 100 yard targets are bogus.
I think you are afraid to test your theories in front of observers.