OK so another update for the Samsung KS8000 line of TVs now that I have been in my new place for awhile and have been able to play longer. Compatibility is still the same, as in being able to see the picture correctly, but the TV firmware is weird with the OSSC.
Line double mode all is good
Line triple mode results in occasional “pixel shifting”, I’m not sure what the correct term is. What happens is that every minute or two what looks like a horizontal line goes from the bottom to the top of the screen and the pixles all seem to shift left a little as the line passes them. That said, the exact same thing happens on my XRGB mini at 720p output, so my assumption is that this is some kind of weird artifact of 720p video on the 4K display
Line quadruple results in some odd aspect ratios (TV changes it, not me) and more importantly, for whatever reason, the TV disables game mode and grays out the option so you cannot select it. While you can make it look fine, at non-4k the input lag on this TV is around 113ms (vs 21ms in game mode per rtings) so this is kind of pointless. 4x will also cause the TV to label the input “PC” and if you change back to another multiplier you’ll have to open the TV input menu and change the input label back to “game console” to set game mode again
Line 5x will do game mode, but the given aspect ratio is noticeably wider than 4:3 once the TV is set correctly much like the 4x mode