@girino I am mining with a AMD 6870 and have tried every GPU miner by you and Gigawatt 
I've found out that Gigawatt's v 1,5 is the fastest one for me. With that one i mine at about 14650 khash. All others are like 10000-14000 khash. Can you tell me if this sounds right or if i have some settings wrong? I don't really understand what the stepsizes are or the -a. (Have tried different settings) 
The reason I'm wondering is why the newer GPU miners are slower for me
I've found out that Gigawatt's v 1,5 is the fastest one for me. With that one i mine at about 14650 khash. All others are like 10000-14000 khash. Can you tell me if this sounds right or if i have some settings wrong? I don't really understand what the stepsizes are or the -a. (Have tried different settings) The reason I'm wondering is why the newer GPU miners are slower for me
Well, all the newer miners rely on some specific optimization, like use of local memory or use of vector types, etc. Those resources are faster in some cards but slower in others. Usually we use our own cards for testing, so the resources that are faster on them get to be prioritized. So in my case, I have a r9 280x, with lots of fast local memory, so optimizations that use lots of local memory tend to be chosen. Gigawatt's card is good with vectorizing, so he always focuses in using vector types, etc. Possibly none of those are good for your card, so it get's slower instead of faster with each new optimization.
I'll try to include a legacy mode (-a 0 perhaps) that rolls back to the code used in gigawatts 1.5, so it can be used in GPUs like yours
Have you tried all 3 of -a options in this new one? -a 1, -a 2 and -a 3? which one is faster?