All it takes to see what the accuracy difference is between perfectly balanced bullets and those only very slightly unbalanced is to measure their unbalance amounts (using centrifugal force at a given rpm spin rate) then sort them into groups spaced by some arbitrary amounts. Full length size a bunch of .308 Win. cases reloading them with those groups of bullets. Then shoot them in an ordinary Win. 70 action with only its bolt and receiver face & lugs squared up for the Hart barrel then epoxy bedded in a plain wood stock. It's easy to see the difference between the perfectly balanced ones with .117 MOA accuracy and those slightly more unbalanced shooting .250 MOA. And the ones a lot out of balance would barely hold 1 MOA. This is at 600 yards where all the variables in the ammo are easily seen. At 100 yards, one would be very hard pressed to tell the difference. It's been done.
If your stuff (you + rifle + ammo) cannot discriminate to that level, any difference will be masked by much larger variables in the stuff used to test it.
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.