I voted no because arena is flat with props, whereas Ruins is much larger (for when people join before strat battles), and contains in addition to flat areas and areas with props like ruins, also slopes and other more varied terrain that is sometimes fun and interesting to fight on. Most duels happen in the flat area, but having the option to go to those other areas is very good imo. It also allows for cav and ranged duels, which arena is too small and not open enough for.