People frequently bring up single-particle self-interference as explanation for Hitachi too. Well, in case of photon the self-interference pattern looks the same as positional interference because of the same wavelength. In case of electron and especially neutron the self-interference pattern would be much more dense than observed one because of the much higher de Brogile frequency than the frequency of the positional quantization.
The wave-like quantization of position is the Pivot Wave. The really important thing here is to understand that Pivot Wave isn't a real wave/object. It is just a description of possible positions of the particle at specific times. Like a trajectory of a bullet isn't a real thing, it is just description of possible positions of the bullet at specific times. It is just in QM the trajectories are wave-like quantized and probabilistically spread - that the non-smooth at small scales structure of our Universe shows its "ugly" face :)
Again, taking the quantized wave-like trajectory description of a particle for a real thing, the particle itself, is the main misinterpretation that has been going for years, especially in Copenghagen interpretation.
Is it possible that pilot waves are ripples in space-time? We should not make strong assertions especially when a theory is young. You make it sound like nothing more than the a regular QM wave function.
Don't get me wrong - i'm not denying de Brogile, i'm just saying that wave-like nature of a particle isn't necessary (and thus isn't proven by ) the double-slit experiment. The single-particle double-slits are never really "single" particle - they always show statistical aggregate of many single particles and thus they are explainable by positional quantization alone (of small specks as described above).
In contrast, Bell’s Theorem can be formulated without even speaking about hidden variable theories: the theorem states that some predictions of QM, well confirmed by several experiments, can not be explained by any local theory. And BM is nonlocal, as well as QM is. In fact BM inspired Bell to investigate non-locality, finally leading himto discover his famous inequalities. Bell was one of the most prominent proponents of BM and wrote many articles explaining it in great detail.
Also here's a wikipedia article that talks about Bohmian Mechanics and entanglement. http://en.wikipedia.org/wiki/De_Broglie%E2%80%93Bohm_theory#...