a minimum of 2.4% gradient has to be maintained
We need to keep in mind that this is the second segment gross WAT limit for twins and that, in general, the aircraft probably won't be WAT limited .. so will do somewhat better. WAT requirements vary with number of engines, and segment .. which, I sometimes think, is overlooked in some of these discussions.
Any takeoff must be predicated on the more restrictive of AEO and OEI situations .. ie if one quits, it shouldn't be an earth-shattering surprise to the crew.