Being a professional student (graduate) makes you independent for FAFSA purposes and therefore you aren't required to submit parental information. It can only help you. Your personal EFC is all that matters in terms of getting stafford loans. If your CoA-EFC is more than $8500 then you will get the full $8500 in subsidized stafford loans. If it is 0 or lower, then you will get the full stafford amount in unsub rather than unsub and sub.
As for need-based aid like Perkins subsidized 5% loans (usually limited to 5000 a year) or institutional grants/scholarships, it requires parental information. If your personal EFC is about 0, then your parental AGI should be less than 100,000 to be eligible for any kind of need based aid assuming their assets are 0 (though it is highly school dependent and many have tier systems). If their income is high, your personal EFC is high, and you don't want to bother getting parental information, then don't bother unless your school absolutely requires it for any aid at all. Personally, I wasn't eligible for need-based aid my first year, but I was for year 2, 3, and I'm assuming 4. In the grand scheme of things at Wayne at least, need-based grants max out at about 10k per year so even the students with a parental+personal EFC of 0 are only about 40k in better shape than you. While there are other need-based scholarships, very few people actually get them. Also, if someone is coming from a background where their parents are absolutely broke and are out of a job in this economy they deserve more aid than someone coming out of college with parents who (at least for the first 18 years of life) were able to be financially supportive.