Perhaps the best thing is that despite getting graffiti'd lots of kids seem to enjoy clambering around on it, and when they see people actually climbing on them are often intrigued and interested and will then try a bit harder etc. Whether this actually encourages them to take up bouldering/climbing as a sport I've no idea though.
Anyone got an idea on what they cost?
Welsh Steel, where you planning on putting them. I reckon Union Terrace Gardens would be ideal or Duthie Park in Aberdeen would be good