I did it in about 2019. I shared a sleeper with a friend. Yeah, the sleeper was tight and the dining car was crowded. But getting on after dinner in London and arriving in Edinburgh certainly beat flying IMO (as a tourist).
I've done both, both were equally miserable tbh
Was 2019 so I expect so unless they replaced them since.
Hm, the Mark 5 carriages were introduced in April and October 2019, so it could have been either just from the year.