They overpaid if you are of the view that gold will go up 10% a year. Most of the analysts laugh at Neumeyer the same way they laugh at McEwen (since both of them see gold going much higher).
However, none of these analysts have a good model on gold prices and none of them can accurately forecast where gold is going. In addition, both Neumeyer and McEwen have not even been close in their's.
We will see in time who is right.