It's come up really nicely
I've stitched a number of mosaics using both a D7200 and D810 in PixInsight and I've found the best way to do it is using the MosaicByCoordinates script first, this does require you to use the ImageSolver script first so that you can add the coordinates to the images first. MosaicByCoordinates will create new images that get fed into another script.
Then you use the GradientMergeMosaic script on the new images. I've found this works quite well myself.