Ok, here's a crappy hack...
Using "Plugins->Editor" and selecting "Testimonials", you can get to the "testimonials-by-woothemes/woothemes-testimonials-template.php" file.
Line 133 is:
$content = apply_filters( 'woothemes_testimonials_content', get_the_content(), $post );
and if you change that to:
$content = get_the_content();
then it seems to work okay. I'm not sure what the "woothemes_testimonials_content" filter was intended to do — it may be intended to "sanitize" the testimonials against people sneaking hacks into them. But if you write your own testimonials and don't allow reader submissions, it won't matter.
ANYway... I'd really like to see a fix originate from Woo on this one, but in case of emergency my answer about should work.