i use the empress stains on everything now charles, metal, emax, zirconia.
It has a much larger range of shades unlike the emax or gc stains which are just a,b,c &d.
Makes it easier to get the shades you want.
For emax monolithic, just pre-condition with fine diamond, then rubbers then apply the gc luster, then just paint on the empress colours you want, vibrate a little, then fire on normal luster cycle.
You can get good shades matches and glaze in 1 fire no problem, and shift around 2 shades fine.
The only benefit with the GC luster paste is you can stain and glaze in 1 hit. If you gonna do seperate stain and glze then the emax glaze works fine, just bump the temp upto 810. if you try and stain glaze in one hit with the regular emax glaze though, it will come out dull.
Saving 1 firing cycle adds up so i think its worth it.