My I-140 (EB1) and I-485 were sent on Dec of 2003, my I-140 was approved at March of 2004, then waited for the approval of I-485 until last week due to FBI name check. Some thoughts on FBI NC:
1. Never give up, and do something instead of just waiting. No big deal, NC is just a process, do not worry too much.
2. Both first lady and congressman office could work. In my case, my company provided the congressman office a serious letter at March of 2007, it worked. Congressman office will figure out a approach to talk with FBI if your case sounds strong and important.
My best wishes to all the people here.