Following up on my own message, one thing to consider is that
generating the figure in latex creates a PDF that takes up the whole
page but the figure is only a small part of this page.  In latex, if I
wanted the PDF to include only the tikz figure, I would do the
following:

--8<---------------cut here---------------start------------->8---
\documentclass{article}

[...]

\usepackage[active,tightpage]{preview}
\setlength\PreviewBorder{5pt}%

\begin{document}
  % Define block styles
  \begin{preview}

[... the tikz commands ...]

  \end{preview}
\end{document}
--8<---------------cut here---------------end--------------->8---

It may be worthwhile providing this type of option to babel-latex?