We should keep in mind that there are other WYSIWYG editors and simplemde 
is essentially just an example (although it's the only one shipped as 
part of a roundup template). The templates (and the WYSIWYG editor) are 
user replaceable, but the backend not so much, so we should try to keep 
the backend stable and instead configure the WYSIWYG editor to match the 
backend.

So I would prefer to add "singleLineBreaks: false" to the simplemde 
rendering config.