I did see that somewhere. Whilst 4k 120hz requires some gfx option fettling, 240hz! well it'd be nice n all but cant see anything powering that for a while.

4k at 240fps! Maybe CS:GO.
I've never seen more than 144hz panels - can you tell the difference between 144hz and 240hz?
I always think of this experiment Linus did regarding very high refresh monitors. The jump to 120hz + from 60 makes a big difference. Refreshes higher than that, not so much.
https://www.youtube.com/watch?v=OX31kZbAXsA
GAming online from home and whether you hit something or not will more come down to the pings of players in the server (Please bring back 60, 90, 120hz servers like in BF4 and set ping limits!)