I have a 63" plasma from 2007. (Samsung PS63P76FHDX). I'm thinking about replacing it with an LG 79UF770V 79" LCD. Will I be disappointed with the picture quality? Will the blacks be all grey and blotchy? Looks like quite a bargain at £2799. The reviews say the 770 models don't have the greatest picture, but perhaps 4K and the extra 16" of screen will make up for it?