Then you go somewhere else. Nobody forces you to take a job with extra risks and a contractual situation that allows others to pull the rug out from under you when the pay-off materializes.

Really, the only potentially bad contracts are the ones that you've signed. So as long as you haven't signed you have negotiation room and if your choice is between being paid 'market rates' versus being paid 'half of market rate + options' and those options are subject to change without notice then you're just setting yourself up for being hurt if you chose the second.

Nothing is set in stone, that's more a matter of self-confidence and knowing when to walk away.

The grant itself requires board approval, so that isn't a huge roadblock. The bigger issue is how much leverage you have. If you're experienced and they need you, getting double-trigger acceleration shouldn't be an issue, and it can't hurt to at least ask for single-trigger...