DRO - Metric or Inch

[DJ Morrow]

I'm looking at a Sherline mill and thinking about a DRO. In Canada, we're officially metric but use of inch measures is still a reality. I thought I could buy an inch machine with a DRO and then the DRO would allow instant conversions depending on what I was milling. But, Sherline offers either an inch or a metric DRO and not one that does conversions. I emailed them and they said that it can't be done because :

"The system reads off the threads of the lead screws; therefore, if you had an inch machine and tried to read the DRO in metric your data would be
incorrect. The threads off the metric screws are finer than the threads off
inch lead screws, so using the DRO electronics in the incorrect mode would
result in information that could not accurately be used."

This doesn't make any sense to me at all. I don't want to start an arguement with Sherline but to me, the conversion should be electrical and done just before the LCD readouts. I've searched the web and inch / metric conversion seems to be almost universal on dro's.

Am I crazy or is Sherline just a bit out of step with the rest of the world ?

[HuFlungDung]

What brand of DRO is it? If it is deducing the values based on stepper motor pulses or something, I could understand their argument. But, if it is using a seperate scale, then it should be convertible.

Buy your own system from elsewhere so you can have both.

[DJ Morrow]

According to his email, it reads off the lead screws. Not sure of the brand.