If you take the deal, then your shares are swapped. There is no tax implication until you sell the new G shares or the new probe shares.

If I am a U.S. investor i would hang on until the dollar rises ( it will again someday ).

The whole game now is to watch the price of gold and the price of G.

If the price of gold starts to slide ( which I doubt right now ) then G will start to slide. You can sell at any point now between now and closing of the deal. You only get the new probe if you say yes to the deal and keep your PRB shares.

If gold continues its breakout, then G goes up. Everyone wins then.

and

NEW PROBE will not be worthless. There will be about 30 million shares O/S with 20 million in the bank. Do the math.