I have learnt over the years from personal experience, and watching the outcomes of others, never, ever, accept a deal with an employer where they structure pay or rewards for future payout. Always, always get the payoff or bonus upfront.

They may want to discuss potential claw back contractual clauses, but again, once you starting your own, they will back down.

The biggest eye opener is that you never really "know" an employer till things go wrong and communication goes legal.