I'd always go with the maps too. If you lose the route, you can have some problems if all you've got is the guidebook. (Although I'd probably take the guidebook as well if its got interest value)
Some people, who have lots of money, have been known to slice up the maps so that they only carry the bit that they need for the walk , plus about 10km either side. This would save quite a bit of weight on the PW.
Peeps who have mapping software, of course, only print off and laminate the bits that they want, and so save even more weight. The trick is to take just enough to cover yourself from wandering off route.