Walking over concrete or clay tile roofs gives a risk of breaking tiles. Concrete or clay tile roofs place a very heavy weight on the structure (concrete tiles weigh 90 kg/m² – a 200 m² home has about 20 tons of roof tiles).
Pressed metal tile roofs became popular in the 1970s onwards and were made of galvanised steel or aluminium with either a painted finish, or a bitumen coating that allowed grit or small stones to stick to the pressed metal / aluminium sheets.
An obvious problem with metal tile roofs is that they often become dented under foot traffic, which makes leaking even worse than usually experienced. WPS experience is that all tile roofs are prone to leaking in high wind conditions. The most effective roofs IMO are long run corrugated metal and long run rib profile roofing (there are a variety of different styles and trade names for this profile). The most attractive roofing IMO is corrugated metal.