[Tex/LaTex] Combining Helvetica and Symbol fonts with mathspec

Question

I want to combine Helvetica and Symbol fonts so that Helvetica handles the Latin letters, while Symbol handles the Greek letters. Mathspec and XeLaTeX does a reasonably good job of this, but I cannot get the parentheses and the percentage symbol (and possible other things) to look right. For example, the following code

\documentclass[10pt]{article}
\usepackage{mathspec}
\setmainfont{Helvetica}
\setmathsfont(Digits,Latin,Greek)[Uppercase=Italic,Lowercase=Italic]{Helvetica}
\begin{document}
\Huge This looks right: $L_e$ (\%)

\Huge This looks wrong: $L_e\,(\%)$ 
\end{document}

produces the following document:

(In order to keep things simple, I omitted the \setmathsfont(Greek){Symbol} command, since the problem shows up without it.) How do I make XeLaTeX use Helvetica for the the parentheses and the percentage symbol when I am in math mode?

Answer 1

load fontspec without math:

\documentclass[10pt]{article}
\usepackage[no-math]{fontspec}
\setmainfont{Helvetica}
\usepackage{mathastext}
%\setmathsfont(Digits,Latin,Greek)[Uppercase=Italic,Lowercase=Italic]{Helvetica}
\begin{document}
\Huge This looks right: $L_e$ (\%)

\Huge This looks wrong: $L_e\,(\%)$ 
\end{document}