I mine LTC on both sapphire and gigabyte (WF3) cards, and the gigabyte ones are infinitely better.
I get about 720khs per card (vs about 660 on the sapphires) with the following settings:
Core: 1045
Mem: 1500
Concurrency: 8192
Vectors: 1
GPU Threads: 2
Worksize: 256
Intensity: 13
I wish I had only bought the WF3 cards..
I could not get my Gigabyte 7970 OC stable past 600k after hours of tweaking, with your settings I'm sitting on 630+
Thanks!