In Radeon Crimson Relive 17.4.1 finally was added support for Wattman on GCN1.0 cards such as HD7970, R9 270(X), R9 280(X).
IMHO, Wattman is more effective and usefull tool to over/downclocking cards - it support changing core voltages in different PStates. Only one bug was - memory overclocking unavailable, but for me core voltage is more important than memory clock.
But in all next versions 17.4.3, WHQL 17.4.4 and 17.5.1 there was returned Overdrive for GCN1.0 cards back.
I want to know - when you return Wattman for GCN1.0 cards? Until that I forced to use 17.4.1, because I need Wattman.
P.S. It would be nice if you give a choiсe to users - what will be installed Wattman or Overdrive.