You could consider using one of the RH Designs timers or analysers (StopClock 500 or Analyser 500) to get as close as possible to perfect calibration of that head to that paper or as a matter of fact to your developer, toner, and working practices. Personally, I have been very happy using 500H with the MGWT and other papers, but I feel there may have been a slight unevenness in grade separation. I cannot prove that, it is just a feeling. The RH Designs devices with "500" in the name have been calibrated very recently, and you can further calibrate them if you wish to.