Welcome to the club!
👉 Anecdote, since you mentioned Mercs:
I was in San Sebastian a few weeks ago. We got in a city taxi that was a Lexus ES 300h (same engine drivetrain etc)... the taxi driver told us that he had three Merdeces E class as a taxi, but that after 150,000 km, the car needed constant small repairs here and there, to the point it was hardly profitable. He said since he had got the ES he was super happy: after 350,000 km he had zero problems with it and was now a Lexus fan.
I'm in love with the IS300h just like you: such a shame they didn't bring the 4th gen to the UK! Ticks all the boxes for me, and very few others (if any) would (the ES is too large).