The ability to edit a comment should disappear once the comment is replied to. If anyone notices a deviation from this behavior, please let me know.

Very soon we'll be adding a WYSIWYG text editor that blows auto-format away.

Related (I think) to vtpeaknik concern :
Also, after hitting "post" it reloads the whole story, that's very very slow if there are lots of comments and one has a slow connection.

I noticed the disappearance of the "Parent" button which allowed an easy access to the primary source but also conveniently sliced out a thread sub-tree.
That would be very nice to reinstate something like that and not only for the sake of slow connections.
Alas, I expect this to be quite a non trivial change in the underlying cogs and wheels.

The ability to edit a comment should disappear once the comment is replied to

Well... that's a bit better but still there is the case that someone is typing an reply and the author of the orginal post modifies it *while* the reply is being typed in (happened with me today).

Personally - I used to like the edit post idea before, because of my non-native English, but frankly in it's current version it can make things worse than before.