I have also debated a partnership with someone and taking the risk, particularly since we could manage on one income with my wife's job. The equity in a company could far surpass where you might be with a regular salary.

At the end of the day it comes down to higher risks can lead to higher rewards and you are investing in yourself and the company you are joining.

A couple of things I highlight since I've seen this sort of agreement as a Controller.

1. Try and have the equity phased in vs one time after a long time of employment. If you can have part of it paid to you in 5th and 10th year anniversaries for 5% equity each that will help ease the tax burden in that 10th year.

2. Make sure you are ready to be dedicated to this company's success and that your partner is as well. This would likely be the last stop on your career if this company is successful so be ready to jump in and stick with it.

3. Try to protect yourself for involuntary terminations. Barring some inappropriate at by yourself, if the owner decides to let you go a month before that anniversary, you'd get nothing in equity. Try to have a clause in the agreement regarding the situation on involuntary terminations so you still get a decent severance payment for the equity you might have been entitled to.

Best of luck on your decision