What they should do for a trade system: purple ->purple, exotic -> exotic, raid -> raid. You still earned something of equal value and will have to earn more of that value to continue. This means you could not power from 20 to 30 without ever having raided once. You'd have to EARN it, but could still acquire what you wanted. I've wanted the Mask of the Third Man for A MONTH AND A HALF. Xur has had the Lucky Raspberry or Knucklhead radar forever. A friend of mine (a titan) buys a single helmet engram and gets my mask... why, bungie, why can't I just give him one of my other exotics that I'll never use for one he'll never use?