I talked to att. murthy's office on the issue of changing employers after GC approval. She told me to give a reason to quit if its less than one year. The reason should not be indiscipline/bad performance or better job opportunity.USCIS does not care about the reason but if you get into trouble later it is helpful to have a valid reason. In my case I plan to give a reason that my employer is forcing me to travel a lot.
Anyone had better ideas?
--- same Murthy office told one of my friend that nothing in law prevents changing employer ,but it is better to stick minimum 6 months. The REASON of leaving employer will be only asked at the time if citizenship if they have the time and dig more in particular case . if you are laid off due to bad performance it is good for you becase you are laid off and you have not left the employer( did not employer knew about your performance before filing GC for you?) and keep that lay off letter with you, you dont have to give any reasons at the time of citizenship, if asked show the letter that you were laid off.