The focus on energy per copy and pulping is looking in the wrong direction really. It's more important to know if a company is managing its energy use efficiently and sourcing its paper responsibly. Less energy per copy means nothing if the factory keeps its lights on all night and runs the machines when they aren't needed. Using less paper doesn't help when that paper was from an unsustainable source.
More generally, debating whether one bad thing is as bad as another bad thing tends to distract people from the actual goal of stopping the bad things.
You make several good points, Polenth: but there are a few you're overlooking.
Energy used per copy is significant on long print-runs, but it is less likely to be an issue for a self-published print edition because sales are likely to be low.
The inks used in printing can be horrendously toxic, and as I hinted in my other posts here, this is a significant issue. It's just as significant, if not moreso, as using responsibly-sourced paper; and a printer's location has to be considered too, as there are different laws and regulations, and a different attitude to following those laws and regulations depending on which country the printer is situated in.
Many offset printers do keep their lights on all night, but that's not because they run the machines when they aren't needed: it's because they run the machines round the clock because they have so many books to print. Digital printers don't tend to work in the same way--it's rarer for them to do long print-runs, for example--but there's also the question about whether it uses more energy to leave the kit on 24 hours a day or to switch them off when they're not needed, and then have to switch them on again and start that big surge of energy as the printers start and warm up.
It used to be that POD books required a special, very dense and smooth paper and it's still usual for POD books to use it: it takes a lot more energy and, I believe, more pulp (have you ever noticed that a POD book is thicker than an offset one of the same pagecount?) to produce that paper. I seem to remember that such paper required specific trees, and that it was difficult to source them responsibly, but I can't be sure because I can't find my notes (I've written about the environmental impact of printing and publishing, but it was a while ago) and my last piece on this was written a couple of years ago, and I'd bet that things have changed a lot since then.
There are so many points to factor in, and I'm not sure that we can single out any one or two factors which are more important than others without a lot more analysis.
And after all this I'm still not sure if this is what the OP meant by the term "autopublishing"! I hope they'll come back to clarify.