I am now using WPforo since March and it's really a great choice much better than my old bbpress forum.
Some members tell me that they receive too many email notifications and would like to be able to filter with finer criteria. One such criterion would be to be able to receive email notifications by subscribing to Topics Prefix. Is this possible? Or is it planned for a future version?
All users can manage their notifications in the Profile > Subscriptions Tab.
Also, you can disable the email notifications coming from "@" mentioning of their usernames in Dashboard > wpForo > Settings > Subscriptions & Mentioning admin page.