My feelings exactly - which is why we're still with this system. For me, this system has the best way of showing thread relationships, and given the complexity and length of some of our threads, that is requirement #1. There are a few bells and whistles that I'd like to have available, but for the most part, the other systems that I've looked at do a poor job of threading, and / or come with so many extras that they're not worth it.
There are some technical issues (like the way that messages are stored and sorted) that are definately clunky with this system and that could be streamlined using something newer. But for now, we'll stay with what that we got.
Don