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..