I've switched to SGminer 4.1 and I wont be going back to CGminer.

Right now I am trying out all the supplied kernels in SGminer, a 48hour test on each one. When I started mining the only thing I was looking at was hashrate but after some reading I realised it's WU that's the most important factor here (Work Utility). Some kernels gives much better results that others but right now I only have 48h results for two of them:

zuikkis @ 1065 Mhz
GPU 0: 722kh/WU:649 (89.8%)
GPU 1: 722kh/WU:647 (89.6%)
GPU 2: 701kh/WU:644 (91.8%)

psw @ 1065 Mhz
GPU 0: 728kh/WU:665 (91.3%)
GPU 1: 724kh/WU:675 (93.2%)
GPU 2: 714kh/WU:665 (93.1%)

The WU should be 90% of the hashrate or higher. More results in a few days.