This doesn't look like a wise statement since it will not only get the technically illiterate to argue against you but the technically literate as well.What both the Kiis and Dutch&Dutch attempt is to emulate a soffit mount, flush mounting the speakers into a sufficiently massy wall absorbs all of the rear projected radiation, and the flush mounting guides off axis forward response along the front walls, hence you hear more direct sound.
Soffit mounting a low frequency driver will give a monopole radiation pattern (equal in all directions). A cardioid radiation pattern is directional and in many situations will be preferable.
Soffit mounting sends the low frequency radiation that would have gone backwards forwards. This raises the output enabling a particular driver to play louder before distorting. The cardioid radiation pattern is created by getting two sources to partially cancel. This reduces the sound level that could be achieved if the two sources acted together to create a monopole.
Soffit mounting removes the diffraction from the baffle edge. This is an improvement at higher frequencies so long as it is incorporated in the design. Better designed speakers will have incorporated the bumps and dips from baffle edge diffraction into the design of the crossover and so soffit mounting these will require more than just a correction for the changed boundary reinforcement.