In the German Wikipedia, we use templates that include a signature, like de:template:Hallo. It's best to use it by opening the full page edit form and put {{subst:Hallo}}
at the end of the page because that allows you to write an edit summary. Or you use it by just putting it in a new section (without a title) and saving without an edit summary. The template automaticly adds the title and the signature.
The New Discussion feature allows to set a custom edit summary without needing to edit the whole page. You don't need to enter a title but since you did not write ~~~~ at the end of the page, the tool double-singes the message.
It would be nice if you find a way to solve this without changing the workflow of users using the old way of editing talk pages.