WIth current TL 2013, LuaLaTeX, and babel I get an additional space between\TeX and nic With polyglossia or using XeLaTeX everything is fine.
Herbert
%%lualatex test
\documentclass[12pt]{article}
\usepackage{fontspec}
\iftrue
%\iffalse
\usepackage[ngerman]{babel}
\else
\usepackage{polyglossia}
\setmainlanguage[spelling=new,latesthyphen=true,babelshorthands=true{german}
\fi
\begin{document}
\Huge
{\itshape\TeX nic}
\sffamily
\textit{\TeX nic}
\textsl{\TeX nic}
\end{document}
