A very interesting analysis. I should have said "you COULD set it to RA" rather than "should". I have looked in our expanded checklists and it's not part of the procedure to do it so I guess it would be best to leave RA set, as you say it may help to prevent the double descent scenario.
Lets hope we never have to find out for real how much traffic you would get in way of if you depressurised over the London TMA at FL350, one thing is for sure, turning off track is not going to solve your problem.