Im wondering the same, i had the uk6300 but i returned it after seeing it was a RGBW panel and got the 55uk6550 thinking it was the same model from this review uk6570 but now im having doubts about the panel i cant say for sure it is RGB and like you said in some websites it says RGBW.
Im looking to see if the 43UK6500AUA is same as the 6570 and does it have a wrgb or a rgb panel