What if clicking on 'watch files' in the apm would result in not only marking them watched but also in an immediate reload of all affected files in the current thread for the sole purpose to find out if there were any errors in them, and if so display a warning in the apm UI?
Not sure if that's possible but the proc apm_source seems to be usable for that.
If that worked, we wouldn't need to change the request processors behaviour to achieve a more friendly dealing with reloads.