Toby, I read your post and found it most interesting. It seems to me your idea of the Infinite Substrate is very worth exploring. To my it bears a strong resemblance to the Pauli-Jung collaboration I wrote about earlier, the unus mundus, the "one world". This is a dual-aspect monistic view of consciousness in that they posit mind and matter as dual aspects of a unity of the one world. This also comports with my understanding of what William James ultimately concluded which was a univesal consciousness he called the mother-sea.

One point I'd like to clarify about IIT. Koch makes clear in The Feeling of Life Itself that IIT is necessarily panpsychist, so it is not an alternative to panpsychism as I think you suggest, but an attempt at explaining how the physical substrate extracts that inherent consciousness from matter. Not sure if you read my analysis of this idea in Top-Down or Bottom-Up but I believe that Koch, as Chalmers has said, assumes what he sets out to prove. I think IIT is on the right track in many ways but is far from the claim that Koch makes that the physical substrate of integrated information IS consciousness.

I'll be watching you for further thinking on your Infinite Substrate.