My oppinion, as a long time p2p player, is that yes f2p should be able to get capes of achievement however, i believe p2p should get special bonuses for wearing the cape, which f2p dont get. eg. runecrafting cape gives a 10% chance of not using a essence (this is not a suggestion just an example of bonuses they could give) this would make f2pers able to show off their capes while p2pers wont feel there getting less for their money just my oppinion :D