Actually there is not enough difference between having -clgreen on or off on either power or speed as I can tell.
I have ran it for long periods both ways, no noticeable impact on money or power. But, the -clKernel 3 instead of -clKernel 1
immediately increased my hash rate as I mentioned earlier, not a lot, but I welcome any small improvements.
The AMD cards with Phoenix work unbelievably well. I never have a crash or anything negative. It just runs forever without any intervention.
It's a great miner. Hope you find your issue with the green setting but unless you get different results than I do I'm not sure you will see much gain.
Let me know if you get different results please.