Benatar's argument is simple: Scenario B (non-existence) is preferable to Scenario A (existence). A 'good' + a 'not bad' is better than a 'bad' + a 'good'. If Benatar's argument is sound (and I'm still trying to establish whether or not it is myself) then the thought experiment proposed by Breakey must be seen in a different light. If one adopts Benatars outlook there would be no benefit in creating a whole new world full of people that otherwise would have not existed. The reason is that their non-existence is not a harm and that the pleasure that they are deprived off in non-existence is not experienced by anyone. Seen in this light the existence of Earth2.0 causes people that did not exist to exist, and, as seen in the matrix, this is arguably a bad move.
There is a great blog post on Benatar's writings here which deals with Benatar's central thesis in a lot more detail than I have in this post.
As always I welcome any comments or criticisms.