Situation: so-so. 4 jobs in 4 years, but good performance/references, obvious talent that comes across in an interview. Sour notes are that I have an unfinished graduate degree (left academia for Wall St) and was laid off and unemployed for 5 months in 2008 because of health problems. Because I've been working for deferred cash for a while, I don't have a lot of savings. Once my back pay comes through, though, I'll be on better ground, but right now I wouldn't want to be out in the cold. Also, I really like the other founders and the work, so leaving lightly might be a dumb decision.
That's a tough call. Take any advice here with a grain of salt, because I don't know you or the people involved. But if I was in that situation, I might ask nicely for a greater stake, and then if they refused, and I thought I was getting below market compensation, I might quietly look for another job.