I don't see any benefit in SDV in excess of the $100M either.
Its not like GXY are going to mine SDV. Receiving anywhere between $250m AUD per annum for a 8000tpa build that cost around $100m. The idea is just not going to get off the ground.
They must be kidding themselves to think that they will be able to mine 25000tpa. How will they ever finance that, its going to cost them around $300m for a build like that, and they will only make $500m per annum. Last I saw it was around $800m a year.