The measurement question is open to conjecture with all machines; how slack/tight are the gib strips, how much backlash on the leadscrews, how good is your eyesight when looking at the dials, do you look at them directly from above/off to one side, account for parallax error, which side of the line are you looking at, are the X axis stops utilised etc.etc.. I have since fitted DRO's (albeit economy priced) to my X & Y axis so I can virtually forget about most of the previous, & having used them to modify the vice jaws on my bandsaw last week I found the measuring to be spot on.
My machines are metric but if I need to use imperial, as when constructing my rear toolpost recently (Hemingway kit,usual disclaimer) the plans of which are Imp, & prior to fitting my DRO's, I simply converted by multiplying by 25.4, or dividing by same as the case may be,so working in either imp or metric should pose no probs' plus there are a plethora of conversion charts available… (Zeus booklet !).. in all cases I check with micrometer/vernier/depth/ internal mic' /anyway, as on occasion the 'Z' axis fitted DRO has sometimes gives spurious readings. (probably due to me not setting it up correctly, or maybe the battery is low/cold?) anyhow I am getting used to its foibles(ea.mach' WILL have its own) & so far I am content with both machines, touch wood, fingers x'd.
Happy hunting
George