Resource use by pbooks is pretty ugly - mostly because they use a lot of non-renewable resources, like old growth forests. Not to mention water. Once you get down to only caring about distribution you''d need real audited numbers I think.
One other thing to think about is to what extent your lissoose replaces a full computer. If I spend a couple of hours a day using a lissoose that takes (say) 1W to use instead of my desktop PC that takes about 200W, that's a reasonable saving. Not enough to pay for the lissoose, but it does help.