I fail to see a purpose with the "middle" stance, forgot the name. It's 10% haste and 5% dodge iirc. Why would you use this?
I use this when I'm in groups where the tank has trouble holding aggro. If I use the damage stance, the tank sometimes cannot pull aggro off of me. There is no point in using the defensive stance since you lose 10% accuracy. And so, this leaves you with the haste stance

Wouldnt it be better dps to just spam ashenhand when you have the jin?
Secret of the Flame adds some very nice dps. I do not use it very often because the jin cost is not worth it since it only lasts 20 seconds. Secret of Ice, I'm not too sure about. The 4 jin cost has made it so I have not tested this much at all.
Anyone have any info on how much dps you can output with jin surge?
I have used this several times in groups. I have even been on Vent with my group members and asked them to tell me when their big attack was ready so that I could hit it, and see how much it effects their damage. I have noticed no difference in my attacks when I have JIn Surge, and none of my group members did either.