Fellow LW-ers of the non-english speaking world: if a native started speaking to you, and insisted on continuing to do so in english, would you get the incessant urge to smack him in the head?

I live in Germany and I do from time to time use English to speak with friends who are natively German. But nobody of them cares about German national identity. As far as I understand many people who do care about their national identity wouldn't just switch to English because it goes against their political beliefs. Two average Frenchman would feel like traitors for switching to English with each other.

And on pronunciation, how do you get that to a level where it is not a sore to the ears anymore? (I must mention that I had a logopedist involved in this even for my native language)

Have you thought about using text-to-speech software to create texts on the computer? I would guess that trains proper pronunciation because otherwise the computer won't understand you.