I think the difference between Harris and Diamond is that the former tried to link some positive cultural features, such as foof taboo, to environmental influences, whereas the latter links the absence of certain features that developed elsewhere to negative environmental influences. I think Diamond goes beyond Harris' correlations and rationalizations of the sort "y turned out to have an advantage in the x environment, ergo x causes y" and carefully considers counterfactual evidence i.e. the presence and absence of suitable species, the presence and absence of geographical isolation. In a word he is more analytically empirical than harris, buit perhaps I misjudge Harris (I read his book quite a while ago).
I think the larger issue is the explanatory power of the 'enviornmentalist' argument. In my view, it goes a quite long way and has a nice twist - it undermines the cultural superiority bullshit. It deflates the claimed intellectual civilisational superiority of the dominant nations by saing that their good fortune is basically good luck (good location, good contacts, early start).
Diamond's argument is most convincing in explaining large civilisational differences, e.g. why simple hunting and gathering social organization survived in some parts of of the world almost to modrern times whereas other parts witnessed development of complex civilisation? But it looses power when it comes to explaining inequal power distribution among advanced civilizations. For example, why did Chinese or the Arabs, who had both an early start and technological edge over the Europeans, eventually succumb to the European power? Diamond make a passing refrences to differences in institutional structures of the Chinese and European societies, but essentially he eschews institutional explanations in favour of what he calls "ultimate" (i.e. material) causes.
In that aspect I think he is a step back from the so called Brenner debate.
In essence Brenner debates the narrowly materilaistic-Mlthusian interpretation of the development of European capitalism by arguing that while population pressure migyht have been the "ulitimate" cause (Diamond's term, not Brenner's). institutional structure was an important intervening variable that made diffrence that can be observed to this day (e.g. the Western-eastern Europe divide). Ironically, both authors are analytically empirical and carefully consider historical counterfactuals, however, Diamond is too dismissive of social institutions.
As far as your claims re. domestication of American bison are concerned - I simply dunno. Diamond claims that bison was unsuitable, and I take his argument for its face value, but I do not have ebough knowledge of animal anatomy/behavior to evaluate thatclaim independetly.
But again, the bottom line is that if reject environmental explanations, we are stuck with the culturalist tripe claiming moral virtues, intellectual superiority, providence and kindred metaphysical abstractions, or worse yet, multi-culti relativistic delusion that being a hunter-gatherer is as good as being a citizen of the European Union.
wojtek