Ok - sounds good - I´ll give it a try. To be honest I only tried the AA methods sinc and still frame, but did never touch the threshhold.
You sir, have an anti-aliasing problem.
When ever you have thin strips of high contrast that start stepping and blending together this should be the first place to look.
bump up the min level to :2x2
and the max level to: 8x8
and then lower the threshold to around 2.5 - 5%
Prepare for longer render times.
I went from 1:23 to 2:24
Now as a proper sell, dropping the exact same scene into the physical renderer produces a render time of 0:08
One thing you may want to do is ditch sinc as the AA method and choose a filter that is faster / has less sharpening...unless it is really needed.
Is there a way to force the extra AA only on the problematic layers via a tag or so? I thoiught I saw that some where but maybee I mix it up with the motionblur tag...