Interesting that you have Noise so late in the workflow, just before sharpening.
Both Topaz, and Nik, recommend Noise to be the first step in the workflow ( after Library functions of course), irrespective of whether you are using their plugins or not.
They say you should de-noise before applying ANY adjustments to your image for best results.
Here's just one link to a Topaz post on this subject, but you can find others on the same.
http://www.topazlabs.com/blog/image-noise-reduction-workflow-tip/
Hope this is useful.