Ok, then this might be true for this special case. You find more infos about the scene management of Irrlicht here:
http://irrlicht.sourceforge.net/features.html#SceneMangagmentI think the comparison to GameCore / BV is another story. You can create special (very simple) Occlusion geometry there to create your own scene management. If you set it up right then it will beat the other methods in many situations. But it needs more work.
For indoor it is another story as well. A system with portals and zones like in C4 or Torque will always beat the methods like Octree, ABT and similar. Only because of such an efficient system it is possible to create rooms with tons of shaders and dynamic lights in C4 while making big indoor levels with dozens of rooms.
The scene management is very important and should differ depending on the game you are making. ABT is better for outdoor but not good for indoor and a PVS system is better for indoors or faked outdoors like you see in HL2 games.
If you are going to make an ambitious project with bigger worlds then this has to be taken into account.
For 2d casual games you dont have to care about it.
