I have an ML7 that came with a full set of changewheels and a QC gearbox – for the reasons stated in the OP, I decided to convert the lathe to CNC operation and now have ELS and Mach 3 control available, which provides any thread pitch at the touch of a few buttons, also any fine feed rate that I may need. I wouldn’t go back to the faff of using changewheels.