I've not carried out specific tests on power cables; why would I need to?
50 Hz down a bit of copper rated to carry the current and insulated for the 240v; not exactly rocket science to understand what is happening in the cable.
If RFI is a problem, then the fault is with the equipment; it should be immune to this.

Again, they made no difference to me. I'm not saying there is no difference for you.

Again, if you are happy with the results, however they get into the brain, real or imagined, then just sit back and enjoy them.

It's your money to do with as you wish.