The important question is if they will be paying a salary and what kind of salary will it be? (will you be taking a lower rate then you make now, etc).
If you are being paid a good salary it would be harder to justify a larger piece of the pie. If you are working for peanuts, or even free, then the sky is the limit.
The initial salary I negotiated for I thought was fair. It was market rate in my area.
The problem is I ended up working way more than 40 hours/week, which diluted my hourly rate.
I see this as a continuing trend. I would have a big problem working 70 hours a week for my current salary, which is why I'm trying to figure out what % of equity would be reasonable.
If you are being paid a good salary it would be harder to justify a larger piece of the pie. If you are working for peanuts, or even free, then the sky is the limit.