Equity is the risky bet 401k substitute (FN1). It would be great if I could trade equity with other engineers to slightly lower the risk of the "all in one company" issue.

It is a myth that I can work longer or harder on demand. If I do have extra energy, I spend it keeping my skills up to date or working on personal side projects (which also keep my skills up). I am definitely not going to work extra for equity just like when I get a 10% raise, I'm not planning on working 10% more time.

FN1: I'm not kidding myself -- I invest post-tax money into mutual funds at Vanguard for retirement.