RE: Foolish to sell If I understand what the BFS is, it's purpose is to provide a conservative estimate of operations, with a 95% confidence interval within +/-15% of the estimate. But remember, this is a conservative estimate. Management has to balance two needs: provide accurate information and not get taken over.
Avoiding a takeover means not letting the company get even more undervalued (hence their continued ad spending), and not dropping news proving that the company is as undervalued as we suspect it to be all at once, so the stock price can catch up. Given the Muguk PEA, I wouldn't be surprised if they're been even more conservative in their estimates than usual. If I'm right, we won't see the full extent of this project until they're in full production.
When a takeover is your biggest worry, things are looking pretty good.