I also find it quite difficult to produce satisfactory results with neatimage against high-frequency AM Screening noise. It always tends to leave small spots of noise untouched...And turning noise threshold all the way up just blurs everything away. Also it often create ringing artifact along edges like greyc does.

I usually use the processing I posted at page 1 of this thread.

some precautions about noise ninja:
1.NN strongly desaturates thin colored lines such as blush lines (making them gray). So be sure to confirm these losses, and mask these areas if necessary.
Also, NN desaturates the whole image a bit.

2.NN sharpens result images by default, you'd surely like to turn sharpening off if NN is not the last step in your processing.

3.NN's profiler doesn't check selection area uniformity like Neatimage does, so don't mistakenly select an area that contains details.