The question was about whether there is more [accumulated] gravity toward the interior or the exterior of a symmetrical spherical mass, ideally ignoring for simplicity sakes local (black hole) peculiarities, and: is it not true, that gravity is mainly on the outside? Even in an evaporating black hole, the interior gravity has to fall to zero at the center, theoretically. or? That mass of dark matter too is inert gravitationally toward the center. imho. so: if you think that the higher outer orbital velocity have to be the result of dark matter in the peripheral neighbourhood, ?? re-examine that please! perhaps it is really because all the gravity is there , compliments of the old fashioned matter and the shell theorem? PS: Even outside the Schwarzschild radius, the same mighty gravity of the Black hole mass that falls quickly to the near center, will only slowly peter out approaching infinity. Adding mass will not change the fact that all the gravity acts toward the outside. Sphagettification is reversed once you pass the event horizon, or max gravity.