Hawking: A.I. 'worst event in the history of civilization'

It doesn't matter so long as your goal is just to make a machine that satisfies your norms for what a conscious, intelligent being should behave like.

If the idea is to fully replicate a human's consciousness, then it absolutely matters, and for all the reasons why functionalism is so appealing: what's floating around a single synaptic ion channel contributes to whether the neuron fires, which in turn contributes to the judgement and behavior of the neural networks it is a part of. Individual neurons are their own creatures with their own agenda's. They aren't simple mechanical circuits.