The problem with back weighted grants (and amazon is famous for this) is that the companies that do it are the ones who ride developers raw and are doing it to attempt to stanch horrific employee turnover. Well, I guess I'm generalizing from the example of amazon, but really, is that the company you want to keep?

My take on it as a startup employee is (1) no, (2) hell no, and (3) your company sucks and you are doing this to attempt to lock me in. Also, hell no.