What is the purpose of the following GO curves: x800-x890-GLOSS-Master and x800-x890-MATT-Master. I assume that the 3500GO is just more GO than the 3000GO.
These are Master curves for printing Targets to have custom curves created. You would use the GLOSS-MASTER for any glossy printing done on any of the X800/X880/X890 printer models. Then you would use the 30000GO curve to gloss overprint the image, and if you needed to the 35000GO curve for certain papers that require a little extra GO to eliminate gloss differential.
If you were printing on Matte papers for the listed printer models above, you would use the MATTE-MASTER curve.