Emptiness and one taste Might it be true that emptiness can be conceived of as the one taste of mind: that the world of mind has only one reality which is everywhere and always the same, unchanging.

Who (which groups or individuals) say so?

And: what reasons are there to believe it is a correct charaterisation of mind?
I think such experiential truths should not be intellectualised. Any intellectual stance - of permanence or impermanence will be outside of non-dual reality. 

Silence is the right answer. cf. Vimalakirti sutra (Wikipedia).


  Vimalakīrti remains silent while discussing the subject of emptiness
  with an assembly of bodhisattvas. The bodhisattvas give a variety of
  answers on the question what non-duality is. Manjusri is the last
  bodhisattva to answer, and says that "by giving an explanation they
  have already fallen into dualism". Vimalakirti, in his turn, answers
  with silence.


p.s. I didn't downvote, I don't object to the question.