OK, so this is pretty close to what I was trying to do, and does produce some banding, but the suggested amount of noise does help break it up.  Now when I try to add a bit of a vignette, I end up with a lot of banding, and have to add a lot of noise to get rid of it.   I guess I'll have to do some test prints to see if the noise will be visible.  I do have another question though, is there a reason you create and use pattern to add noise to the grey layer, instead of just adding noise via Filter>Noise>Add Noise?