Hi NightCabbage, I also did a quick test of PDF export from Expression, and as far as I can tell the PDF it produces has the correct size in it.

So possibly the scaling is happening during the import into Inkscape, look for an option in there to turn that off.

Also you might try going MoI to AI , AI to Mayura Draw, Mayura Draw to SVG, SVG into Inkscape and see if that works better for preserving unit size into Inkscape.

Also make sure in Inkscape you have your units set to mm, and not something like "px" units or something like that, if you had different units set there that could explain why you were seeing the size as different values at different times.

- Michael