Once the NFP US site was done, we started to work on the Canada version. This site would use some of the same templates/components, but it wouldn't be a 1:1 match.
The challenge was to structure the front-end architecture so that we could leverage the same SASS collections but also accommodate differences and entirely new components.
The ultimate goal was to single-source as much code as possible so that if a component changed, it'd change across both sites. So far this has worked out well.