Suffice to say, [WP-Syntax] does the job fine except for one very annoying issue. Whenever you have any kind of special characters in your code (which you inevitably do e.g. <, >, & etc.), these always render as their escaped representations.

It only happens with the WYSIWYG editor for writing content (which the tool's FAQ recommends turning off) but there's a better solution that Alan found - change a line of code in the plugin to use the htmlspecialchars_decode function to rid your install of this pesky escaping bug.