"I wish I knew whether the unimpressed commenters got what Shane Legg did, just from hearing about Special Relativity; or if they still haven't gotten it yet from reading my brief summary of Barbour."

Hard to say. I don't really see the difference between "time is 'just' a coรถrdinate in 3+1-dimensional spacetime" and "time really doesn't exist." Even if we can get rid of the t in our equations (because we never personally observe a t out there in the world, but infer it from our memories and clocks and such), something still has to account for our memories, and clocks, and the apparent changes in what we perceive: for things to be otherwise would be a violation of Egan's Law. I don't see why it matters whether we call this whatever-it-is "causal relations within configuration space" or whether we give it its own coรถrdinate and call it time.