Watched Phil B's wick video..
Not too much surprises. He noticed things that I've noticed too. Organic cotton having an off flavor at first, and just overall not being that great. KGD and rayon offering clean flavor immediately, pure flavor, and quick wicking action. Rayon offering a little quicker switch when changing flavors and gunking a little slower than KGD.
I have found more of a flavor difference between rayon and KGD than he reported. Rayon offers a subtle, but still noticable boost for many juices I've tried. My guess is he was using too much rayon which negated that effect. I overstuffed my KFL with rayon and while it performed great and wicked well, and the flavor was good, that flavor wasn't as saturated and potent when using less wick. Either way, I think the flavor differences aren't really that noteworthy overall. One may work better than the other depending on the juice and someone's personal preferences, but they both provide amazing flavor.
Like Phil, I also don't notice a difference in throat hit, vapor production, or nic delivery between the two, though some have reported that they do.
One bonus to KGD he didn't report on is it's the easiest and quickest to wick, and best at providing repeatable results without practice. KGD and CCr means there's two pretty fantastic options for wicking that in my opinion are heads above organic cotton, sterile rolled cotton, and silica. KGD for those who get a sore throat from CCr, and CCr for those who always notice a cotton taste with any cotton.