I think we do agree... "complexity alone" certainly will certainly not give rise to consciousness. Consciousness begins with feeling and separating the "I" from the "other"; I feel hunger, that there is food. That's why I said we'd have to evolve it in a simulated environment, one in which there are things for a nascent consciousness to feel. So in that sense yes, it depends on the substrate, but the substrate could be virtual, simulated on a powerful enough Turing machine.