I take it that the primary "cold fusion" phenomenon reported by many experimentalists from Fleischmann and Pons onwards is, in a metallic, ambient T, environment:
D + D --> He4 + heat
and the concomitant absence of the normal collision channels
D + D --> He3 + n + gamma
D + D --> H3 + p + gamma
I view reports of other, probably related, phenomena, such as nuclear transmutations in Pd foils, whilst interesting in themselves, to be of second or higher order and more indicative of improvements in the technology of detection than anything else.
There are clearly at least two things any explanatory theory must explain:
1. How the overlap integral for pairs of deuterons can be many orders of magnitude greater than the absolute upper limit "proved", within the confines of their assumptions, by Leggett and Baym in Physical Review Letters, Vol. 63, p 191.
2. Why there is no short wavelength radiation, despite the nuclear dimensions of the deuterons ?
Next, any theory that requires two separate explanations for these two "mysteries" must be regarded with the utmost suspicion. Whilst it is conceivable that mainstream physics has made one oversight, it is really stretching one's credulity to suppose that it has made two bloomers, and that within a context as well researched as hydrogen-in-metal physics.
Such "dual explanation" theories always look somewhat ad hoc.
Next, in view of the generic nature of the two "grand mysteries", it seems very unlikely that they only show up in a CF context.
For this reason, and also in view of the unremitting hostility of much of the mainstream, I consider the whole quest for a theory of CF to be fundamentally misguided. Rather, we should be studying metal hydrides with an eye open to ALL the possibilities offered by quantum physics. It is then more likely that one of us will discover some overlooked aspect that, whilst not specifically CF-related, comprises within itself the germ of some mechanism that may lead to a full explanatory theory.
In short, I think that everyone has been blithely running in where angels fear to tread.
Moreover, in my opinion, untold damage has been done to the credibility of the experimentalists by the numerous amateurish attempts to explain everything by people who are ill-equipped for the task. For example, I wonder how many of the would-be cold-fusion theorists have taken the trouble to study the large literature on quantum hydrogen states in hydrides ? Would any of them know how to derive the band structure and effective adiabatic potentials experienced by a hydrogen nucleus in the metallic environment.
Of course, it may be that the explanation for CF lies outside the confines of the standard model of physics. In that case anything is possible, of course!