Hey, glad you managed to get this to work for your theme!
I used the same "hack" to add a "parent comment" link - by just pre-pending it to the comment text as I wrote here:
I'm also thinking that maybe the comment styles of Google+ and Facebook are pretty elegant. They have a effective "comment depth" of just 2 and seem to not have real problems with long discussions.
Haven't yet worked up the courage to implement that though!