We're not even getting to the topic of elevation (yet). The US Survey Foot is 1200/3937 which is a not a clean value that terminates after a few decimal places.

We're not even getting to the topic of elevation (yet). The US Survey Foot is 1200/3937 which is a not a clean value that terminates after a few decimal places. With high grid coordinates (X,Y), your origin is based at 0,0 as origin. When you scale between metric and US Imperial, if you're not using enough significant digits it impacts how the model scales. This can cause a difference of 1 foot or more from my experience. Floating point operators also become an issue especially in CAD. Standardizing to one number is a great start.