This is a public forum where we pretend to attempt to communicate with each other. Using units that people here are familiar with is key to that end.

It's bad enough when people use Fahrenheit.

"mt" is not a recognised abbreviation for meter, nor is it taught as so anywhere. As non-standard it just leads to confusion and questions. I for example first though it's some weird measurement unit used in marine navigation, like nautical mile.

So yes, don't use mt, just use m.