Actually, I've found the boards where the entire thread is "dragged to the top" if there is a new post in the thread seem to lose their purpose in at least 50% of the cases. People will post and say nothing, just to "drag" the entire thread to the top.
At least here, if you see a post on top, you know it's new. Plus the time/date notation of last post in a thread is fairly easy to follow.
And of course there is the option of clicking on the e-mail replies box, and having any replies to your post delivered to your mail box, no matter when they're made.
PLUS on CM you have the option of setting the boards to read in either "flat view " or "threaded view" . In "threaded view" you see not only the time and date of the post, but the author as well. You can then read the individual reply without having to scroll through all the posts.... if that's your choice!
I think different boards softwear have their strenghts and weaknesses. I find ours very easy to use.. but then I've had lots of practice <G>