I have been playing around your extension for the past couple of days and I am absolutely loving it. I would love to see some minor additions to it if you welcome feature requests.
1) An additional setting that enables Ajax Preview but disables Ajax submit. Would that be possible?
2) Able to make the 'quote' button go to quick reply editor instead of posting page. (Right now, if you click on the quote button while still typing in quick reply, the already typed in text doesnt carry over to the posting page.)
3) When attachments are added in the quick-reply and then the post-reply button is clicked, the text is carried over but the attachment isnt.