What exactly is the point of specifically 'inverting' buck/boost converters?
since I've found very high efficiency (~95%) buck converters that seem
  like they could be adapted to my application easily, should i just use
  them instead of these specifically 'inverting' regulators that
  generally have 10% lower efficiency (because the product pool is
  smaller)?


You may have found a buck regulator that is 95% efficient but this will undoubtedly be a synchronous buck converter that has an in-built MOSFET to replace the normally external diode. If it has an in-built MOSFET or diode then you can't use it to create a negative voltage.

Use an inverting type for simplicity - that's what they are designed for and, if you haven't found one with low enough internal power dissipation keep looking. It might help your cause if you state what power losses you can suffer, what input volage range you have and what output voltage and peak currents you expect.



Added section to give some insight into an inverting converter's efficiency.



When the input supply is connected to the inductor there is no transfer of energy to the output i.e. the output capacitor has to provide all the load current. There is only energy transfer when the input supply is disconnected by the switch and the inductor reverses its terminal voltage to circulate current into the storage capacitor and load.

Compare this with a buck converter; When the switch closes, current passes through the inductor to the capacitor and load thus simultaneously charging the inductor and providing current to the output. When the switch opens, current remains circulating through the inductor AND the capacitor/load.

This ultimately means that a buck converter can more efficiently deliver power to a given load because the charging currents are slightly less and the \$I^2R\$ losses are reduced.