But that's exactly the problem with the 'unicorn' idea - the appearance of contributing to the company is more valuable than actually doing it.

In a very small startup, you're not going to be able to fake it - but by the time the company's at 30ish people, it's not so clear cut. Who's the most valuable developer in my employer? I'm not on the dev team, so I don't know. They all seem to be doing great work, but I don't know the details.

Do we credit the sales guy for landing this big contract, or the operations guys that made sure their trial system worked, or the devs who wrote their custom integration?

If you're not involved in that project, it's going to be hard to judge whose contributions deserve what share of the reward.

Basically, it's a neat reward system, but I don't think it scales very well at all.