Yup thats totally fair enough. All preferences. For me, I wouldn't feel comfortable chasing FPS for £1500 - £2,000. I don't mind for £500-£800 getting a nice increase in FPS but above that price range, I want something trans formative to the experience which both ultrawide, VR and triple monitor setups offer in my experience. 3D gaming also did the same but its a pain to get working with Geo-11 drivers.
High FPS is nice.. its noticeable but its not trans formative. As I said, at 3440x1440, for 99% of games, a 3090/3090TI would have definitley done the job and got you to a decent number FPS-wise. Its simply not a demanding resolution.
I'm not sure why you keep talking about OLEDs. As I said before, I only game on OLEDs and I'm well aware of their positives (and negatives). I hate VA & IPS panels.
Where the 4090 comes into play is at much higher resolutions IMO.
An upgrade path for the alienware ultraide IMO is triple 42/48/55 C2 OLEDs. They have a few drawbacks but in the right space, they're going to look downright cinematic and ridiculous compared to the ultrawide you have. For me, the 21:9 Alienware felt like a monitor. The big OLEDs feel like an insane experience - nearly as cool as my projector - but each to their own.