IO540
I have asked and asked and have never come across anyone who has ever heard of FM interference having actually happened.
I'm not an engineer, but I seem to recall that the issue was created by the desire of government to free up radio frequencies for commercial use.
It thus seems logical to conclude that even if there isn't any interference now, there may be in the future, if there is a take up of the extra capacity.
Unless one views this whole thing as a conspiracy to persuade people that private flying is too expensive to start/continue, then maybe the FM immunity issue is a future problem being dealt with now?