I "ran" NYC last year with Plantar Fascitis. It was no fun. It was my third marathon. I hurt my heel 8 months earlier. I went to a podiatrist, physical therapist, wore orthodics and did all kinds of stretching. Nothing worked. I trained and did NY by the Galloway method as a last resort. I should have sat it out but needed to run NY for personal 911 related issues. My time was a full hour slower than usual and I was in great pain. The Willis Street bridge metal roadway (mile 20) was extreamly bad. If you officially withdraw from the race your lottery pick is good for next year.
As for the injury, I found a good running shoe store owner more helpful than all the docters. I changed running shoes. Then I went to a very good regular shoe stores and bought very good shoes to wear when i'm not running. I can now run with no pain and am training full force for the Twin Cities this Oct.