Right. Based on my own understanding, for a normal CatI we need 2,1%, take off EOI/contingency 2,4% and a normal SID 3,3%. Required take off climb gradient ends at 1500 AGL. So your reduced N1 provides a thrust setting (on a balanced T/O) that will either enable you to stop before V1 or get you to 1500' AGL on OEI without hitting terrain. If terrain is an issue for the required ROC an emergency turn/contingency procedure is constructed. This will require a lower ROC of 2,4%.
So, basically if you end up OEI close to max landing weight, or if a higher missed approach climb rate is required for the approach in question, you should consider your options (increasing DA/MDA accordingly).