My 2p Kev.
I don't use the car at all, I do 4k miles per year and 2.5k is my yearly alpine trip. But it's there when i want to take it for a spin, a track day, a weekend in Wales or a Sunday blast. I've never SORNed it because I want to be able to drive it when I can, spontaneously, good weather, Sunday, nothing else planned, yes please
Why haven't I sold yet? Cost-benefit analysis, to get something better (for what I want) I'd have to part with a lot of cash, which I'm not willing to do. Love cars but they are not my No1 priority, far from that actually.
In your case, you are lucky enough to have changed a few cars in your time and by the sound of it you can go out and buy something else that does the job for you. I'd say sell mate. Cars are not special objects to be kept in the garage, mint, for the next owner to enjoy. The reason I'm not driving mine is simply because I haven't got time but when I do I love it.
To sum up, if the thrills you are getting when driving it are less than your itch to sell/change then go for it