If the posts are validated anything like in my forum and chat, the problem is that "illegal" characters like < and > are turned into entities < and > before the smilie codes are converted into smilies.
Another thing I noticed when trying out the "new" features:
There's no reason to wrap most of the new elements(<ul>, <ol>, <li>, <blockquote>, <hr>, <p align="right">) between <br>s, they'll break lines by themselves.
The additional <br>s just make the post too "spacey".
But of course Sangiro knew all that, it just isn't a high priority.