Some things I noticed recently.
A thread can run to 50 posts before a second page is required. After 50 posts the only pagination links are at the bottom of the page ... and thats a long way down.
Also there doesn't seem to be any way directly into the end of the thread. Recent discussion/Active Discussions will always take you to the top of the first page. Even posting a reply will return you to the top of the first page in the thread.
The url recognition pattern is a bit too strict. This is a legitimate url, http://en.wikipedia.org/wiki/Gecko_(layout_engine), drupal is losing the "(layout_engine)" at the end.
Thanks for your comments.
I will look into solutions as soon as possible.