I am not sure we can assume the resource is 'double'. We would need more drilling even to guess at that. Various folks have mentioned that the Whittle process is very conservative but in my own calculations I simply use 1.5M tonnes. Really, any more than that is almost irrelevant to the valuation as the discounted value to mining out that far approachs zero. Open at depth makes for great blue sky talk but really it is the selling price per tonne that will cause the true valuation to be shown. Which is why there has essentially been no further depth drilling - the focus and the funds are fixed on the selling price and testing.
If this were a typical gold property, they would be drilling the snot out of it to increase the resources but we don't need to.