The main thrust of ultra-light travel is that you look at lightening the heaviest items first. That is why eg threadless headsets are great for tourists, they eliminate 2 heavy tools. Similarly, some of the hubs which dissassemble with allen keys remove the need for cone wrenches.
Shoes are always a dilemma and seem to be the biggest, heaviest items I carry. The true ultra-light rider would take only one pair.