Glad to hear it's still being worked on. If there's any info I can provide to help reproduce it, please let me know.
Other people having the same issue, if it helps find something in common:
http://forums.amd.com/game/messageview.cfm?catid=475&threadid=177635
http://forums.amd.com/game/messageview.cfm?catid=475&threadid=175145
http://www.tomshardware.co.uk/answers/id-1916025/audio-stutter-crackling-vsync-crossfire.html
From what I can tell, it isn't specific to one brand of card or motherboard, so it is very odd indeed and I can imagine the trouble in finding the issue when there doesn't seem to be a clear unifying cause.
All I know is the problem disappears entirely when I disable my 2nd monitor. disabling vsync helps, but DPC latency is still high and introduces stutter, so disabling any non-eyefinity displays is the best way to go.
Thanks Dev, very useful and I'll pass those links on.
I've already taken a few specific reports (including yours) but every time we've tried to repro it on similar systems everything has worked normally. We'll keep trying. If anyone else is suffering from this, please feel free to drop me a trust.