Cache clear is not aggressive enough

We are using just drupal_flush_all_caches() (which is an equivalent of drush cc all), to get rid of any garbage accumulated before doing db dump (and sed based filtering on the fly), while drupal_flush_all_caches(), despite its name, purges only some core bins and explicitly excludes cache_form bin.

The problem is that cache_form bin easily grows out of control (like 500 MB or more) and as a result, not only slows down any task involving backup (db dump) but also easily and silently (!) breaks such tasks, with no helpful debug message, because we proceed even if the db dump effectively failed and there is no backup for further actions, like clone or migrate.

We have seen this too many times and finally determined it was always a result of having cache_form bin full of accumulated garbage.

Now the question is: should we add only:

cache_clear_all('*', 'cache_form', TRUE);

or maybe nuke all existing cache bins?