Modern OLED's are bright enough for living rooms, not as bright as LCD's but more than adequate.
The x900e is a very good edge lit tv. I'd take it over a 55" oled because of size. I'd take a 65" oled over it if it was an option, but I see its not. I'm in the marketing for 77" screens right now and its even a harder choice, spend 10k on a 77" OLED or 6k on a Sony z9d.
I will warn you though,Sony's Android TV is the worst operating system ever made. Horribly buggy, crashes, slow as hell, ugly as hell.