Did export_comments.bml break? I'm getting empty replies when I request the url.
I think the quick comment's UI and the preview page's UI is wrong. Both look very similar (2 buttons and a checkbox), these things present the same basic options (post, preview, and spell check), but they are very different. To make matters worse, the quick comments preview leads to the normal comment page. In fact, the buttons at the bottom of the 'new entry' page present yet another way to again present the same three functions (this time with three buttons).
On the quick comment box:
[post comment] [more options] [checkbox meaning: don't post comment when you click post comment (!!!) but preview and check spelling instead]
On the preview page:
[post comment] [preview] [checkbox meaning: also check spelling when you click preview]
On the New Entry page:
[Update Journal] [Spell check which also previews!] [Preview]
You know the jokes with the button you have to click but that keeps jumping to a different location when you approach it? Well, this isn't all that different, except this is not meant as a joke!