Package cmap or `\input glyphtounicode`?

I'm sending PDFs to some folks who are supposed to copy some of the content elsewhere. It is important that my files are searchable and copyable (while I doubt these words to be proper English...)

So I'm using the package cmap. Recently I have been told, that cmap comes with a limitation, and indeed the manual says: »The main limitation currently is inability to work with virtual fonts, and this is because of limitation of pdftex, and may be resolved in a future versions of pdftex.«

In a question about ligatures and the libertine font here the advice was to use

\input glyphtounicode\pdfgentounicode=1

instead of the package cmap.

The pdftex manual on p. 29 explaines:

The glyphtounicode.tex file (distributed with pdfTEX and other software) contains thousands of such definitions, covering most common glyph names. ... LaTeX users could load the cmap package to achieve the same effect.

I can't find any hint to the limitation, which is mentioned by the cmap manual. So my question is:

Does \input glyphtounicode \pdfgentounicode=1work with virtual fonts? Has the limitation mentioned in the cmap manual been resolved?