It seems that quite some few users have signatures that do not have properly balanced HTML, which might break pages when they will sign pages after everything is switched to remex. This might be unnecessarily disruptive.
We could find all non-default signature preferences, and parse them with the linter? and find the users that might be with a broken signature very soon. Then we can choose to leave bot messages, or display an in browser message or simply reset the signature.
1: db query + bot
2: or php check in session check + special page asking the user to reset or fix preference
3: default JS gadget that checks the preference in session and presents user with option to reset or fix in his preferences.
4: Have remex lint check before saving signature in preferences
Might significantly ease transition.