Issue 1: Ignoring the User
The ‘default units’ user setting in the Inkscape preferences seems to be neglected. The user’s choice is not taken into account consistently. In other words, no matter which unit is selected, Inkscape defines stroke, calligraphy, etc, in pixels.
Issue 2: Inconsistent unit display.
Unit names and/or symbols are not displayed consistently in Inkscape (e.g. sometimes: px, sometimes pixels)