Seeing red

[The Grand Nudger]

I don't know how you've got to this, thinking that I'm trying to 'bait and switch' you  

Not you personally, man, lol.  Our minds play implicational games with us.

First of all you can cross off "a personal god" from the above because I would not even hazard that as a possible alternative.

You did posit it, that's what theism is. 

But the second one, yes, if I could not even rely on the assumption that system X produces conscious state X... that system X in exactly the same state could produce two different perceptional states, then I would, myself, have to start thinking about other alternatives and probably give up on even trying to understand the brain and would probably end up going in Bennyboy's direction, of idealism.

Why, how does it follow?  You will have determined that something other than brain is involved....but not that some other fundamental "stuff" exists or is necessary..or that the brain is not involved.  We already think that something other than just the brain is involved in mind, in consciousness. Neither dualism nor theism (nor idealism) are required in order to account for this..merely an environment. If I found that two identical..or lets say vastly similar structures differed greatly in their perceptions -if their structure could not account for or explain a disparity-..I would look first to environment...as you might when trying to determine why different human beings perceive things differently, or indeed have a different experience of consciousness.