I think we have to differentiate between different types of terrain contours here. For me I would be looking at localised terrain for buildings to be placed on not canyons and valleys which use only curved contours. When dealing with buildings and landscaping though there is usually a mixture of curves and straights - for example most areas of contact between the building and the landscaping will be hard straight lines not curves. So holding out for a solution that can work for all types of terrain work.