This has definitely been mentioned before (because Ryuji and I brought it up), but it's been so long (months) so it probably wouldn't matter anyways.
I definitely support having a quick reply function to the forum 100%. Reasons being in form of 3 major points:
1. Instead of redirecting the user to the posting.php page, it will open up a small window directly underneath the last post. This saves waiting time for both the redirection to the posting page and back to the thread or forum. In short, it's nice, punctual, and efficient.
2. For users who are not going to respond in with a huge amount of text, images, videos, or links, or anything fancy, this will be perfect. One does not have to waste time traveling between pages to post something mundane or short. Responses like, "Lol, that was funny" or "Thanks for the upload" would be so much easier to type than to go to the posting page and back. (Least for me, with bittorrent running, internet is not as fast as it can be) Also another reason is for those who are currently debating a topic, and this will ensure a rapid response and fluid flow of debate. In fact, this will be perfect for Motemote with all those one-liners I see.
3. From what I remember, the quick reply function had the basic capabilities: editing, deletion of post, html/BBcode support, and the like. For users who are used to posting, they can easily input memorized code into the post with no problem and respond faster and forget. And if you wanted to edit it with more functions located on the posting.php, there should be a link that redirects a user back to the posting page for heavy and prolonged editing.
Anyone else who supports a quick reply function, please support.