Firefox has a notoriously sticky cache. I too had members complaining that topics did not refresh on new posts. I think I fixed the problem with mod_expires in htaccess - something like:
# HTML ExpiresByType text/html "modification plus 60 seconds"
Then you do the same for your images/video/css/js in times appropriate for your server and board. Since doing the above none of my members have reported the stale Firefox cache issue.
Before I had access plus*** and that did not work at all.
Thanks, still that could confuse caching plugins, since we use them for the rest of WP site?
(WP 22.214.171.124 ?)