When I got my gc I asked one immigration lawyer who has 12 years of practice and he said that he has never heard about such cases. Just think about it: you are the right immigrant for this country, making money, paying taxes, why they would revoke your gc ? Now they want to legalize even illegal immigrants who have crossed the border illegally.
Besides remember about AC21 law: if your I-485 was pending for more than 6 months then you should be fine. Some lawyers have dual representation and they do care about sponsoring Employer as well that is why sometimes they may say no, work for at least 6 months or one year though they prefecty know that there are no real cases like you described.
Good luck to all of us, H1B -> gc -> US citizens.
Alex.