Unfortunately you get yourself into a bit of a dilemma with this workflow. If you want to use Nik or some other specialized sharpening tool, you really need to resample to the final print resolution first and then apply your specialized sharpening as the final step. I see two ways of doing this:
When I'm ready to print is where I think get confused. Do I want to disable BOTH Interpolation in Qimage as well as Final Print Sharpening? The idea being that the image has already by resized to the exact output size I want and fully sharpened for the output device by NIK?
(1) Upsample in PS and just apply Nik there to the final/upsampled version, then print in Qimage without sharpening disabled. If you print in Qimage using this method, Qimage by definition will not do any resampling because it will see that the final size is equal to the size it needs to resample to.
(2) Upsample in Qimage first, then load the upsampled version in PhotoShop, apply Nik, then print in Qimage without any sharpening. Using this method, you can make use of Qimage's upsampling methods which are better than PS.
Mike - Using Option 1, when you say 'print in Qimage without sharpening disabled', are you saying that I should NOT use any Final Print Sharpening in Qimage?
Thanks again for the advice Mike.