The reason you get no hard answers is because there is no hard RESTful standard. So I can only suggest that you create a hard standard and stick to it within your own APIs
I used this as a guide for RESTful services http://www.vinaysahni.com/best-practices-for-a-pragmatic-restful-api
It says respond with a 204 status and an empty body
I stick to those standards and document them well for anyone who wants to use my APIs