Very menacing, Seth!
I love the central band of cloud, near photo realism, but the near and far edges seem a little noisy, I agree, a little less edge sharpness would do those areas the world of good but I fear you might lose the detail in the central band by doing that.
Nice job though, it takes patience, and guts, to fill TG2 with this much volumetrics!
I know you'll probably tweak this, you usualy do, can't wait for the re-run...