If I were in your situation (where I liked the company, and had decided that I didn't want to try to ask for a portion), say that you're not going to sign anything without having a lawyer look over it with you, and ask them to reimburse you for your lawyer. That way if they need you to sign it, then they can pay for your trouble, and you can find out if there's anything important and get all of your legal questions answered (including finding out if you have any bargaining power). If they don't need you to sign it, then they won't pay for your lawyer, and you can go on without signing something you don't understand.
