Until the X arrived, I was playing the game on an S and, weirdly, the latest patch (presumably the one that made it X-enhanced) seems to have buggered a bunch of stuff up. On top of the usual tearing there's now a bunch of occasional graphical glitches (parts of the screen briefly turning green/blue/purple etc) and -- along with the tearing -- it's making the whole thing rather unpleasant to look at...
Switching to the X version on Tuesday night, the tearing's gone completely. In fact the entire thing is somewhat dreamily smooth now. However I wasn't particular blown away by it until I did a 5-lap Singapore race last night, with my headphones on. Singapore just looks beautiful in 4K HDR and (with the headphones) I found myself just completely lost and absorbed in the experience. There are moments on that track (in the last few corners) where things get rather gloomy looking, but with vibrant greens and purple lights reflecting off of the cars and tarmac. But then you enter the start/finish straight and everything flares up in bright white light under the stadium spot lights. The contrast is just... wow. I think for a brief moment, my brain got tricked into believing I was there.