Jon, find myself with same dilemma, but having sorted most of the future problems, radiator, air con pipes, all new brakes, discs, tyres, sub woofer etc. etc, I came to the conclusion that I would be driving another Lexus, at some point having to do the same. I do about 7k miles per year, so mine should continue now for a decent time without further large outlay....... but it is very tempting, for not really a large cost to change. I think I am too attached to mine, but plan in future to change for an LC 500, the last V8 probably to be made, when the prices become more sensible.
I think in your situation I would go with my heart , good luck Roger