I'm using Charter (with the mathdesign package) for my main text font.
As mathdesign isn't doing a good job at kerning (see "NOP." and "DEF." in MWE), I'm additionally loading the charter package as suggested in this question.
In addition, I have quite a few units with \micro prefixes in the text. I would like my numbers and units to be in the same shape as the surrounding text. However, when loading the charter package in addition to mathdesign, the mu changes.
What can I do?
\documentclass{scrreprt}
\usepackage[bitstream-charter]{mathdesign}
%\usepackage{charter}
\usepackage[detect-all=true]{siunitx}
\begin{document}
Testing the kerning with two examples: NOP. DEF.
Testing the ``micro'': \SI{1}{\micro\metre}
\textit{in italic text: \SI{1}{\micro\metre}}
\end{document}
Example 1: bad kerning, nice detection of surroundings in siunitx

Example 2: better kerning, no detection of surroundings in siunitx

