This is probably the best equity compensation plan for pre-IPO companies I've seen so far. Vesting schedules for a fixed quantity of equity have always irked me

This is probably the best equity compensation plan for pre-IPO companies I've seen so far. Vesting schedules for a fixed quantity of equity have always irked me for the same reason Max explains: they assume a constant value over the life of the vesting, which is almost never the case in a pre-IPO startup. If I was choosing between multiple offers from startups, the ones using this model would have a huge advantage in my book. The one (big) issue I can think of is that it does not provide a way to value the common stock. The valuation events in a startup will very often be investors purchasing preferred shares. Preferred shares tend to be worth quite a lot more than common shares (and the gap tends to be larger the younger the company is), so assuming a 1:1 value between them will severely undervalue the common stock grants.