Love the site and I intend to use it.

The wiki approach would be great if the data was laid out appropriately. Community-edited wiki might lead to a singular view of what a good path would be.

The benefit of a multi-axis rating system is that you could lay out data using different permutations and add/subtract inputs (e.g. rater's experience at time of rating/age/hell, maybe even personality type). I'm sort of modeling this off of robust scientific questionnaires.

It does seem to require some more user involvement, but nothing a fantastic UI couldn't fix.

Do you mean hackerbooks.com or learnivore ? (or both ? :-).

I would love to be able to build something like you describe, but I suspect it will be time consuming, that said!