KU6000 with 50' is VA too. So, with no use of 4k you'll go with k6300?KU6000 is an UHD model so SD picture will look worse. Otherwise they will be pretty similar. The K6300 should have a VA type panel whilst the KU6000 likely uses PLS so in which case the K6300 would have higher contrast.
That's where i found the information. I thought it was reliable.Where are you getting that information? If its displayspecifications.com that is not an accurate source of information, manufacturers don't give out panel information and I know for a fact there have been 50" KU6000 spotted with PLS type panels..Samsung are notorious for the panel lottery, you could get lucky, you could not.