Re: \ac in corpo minore ma solo fuori da MakeText[Low|Upp]erCase

Anzi, così non scomodo nemmeno etoolbox: 🙂
`\makeatletter
\pdfstringdefDisableCommands{%
\let\textsmaller\@firstofone}
\DeclareRobustCommand\ac{\textsmaller}
\newcommand\old@uclcnotmath{}
\let\old@uclcnotmath\@uclcnotmath
\def\@uclcnotmath#1{\old@uclcnotmath{#1\def\ac##1{##1}}}
\makeatother`

Ciao,
Antonio