Just found out about a new threat tracking mod that's available. Threat/Omen has been written in response to increasing concerns about the heavy CPU usage of KTM. It's been written as an ACE2 based, event-driven mod rather than poll-based like KTM.
You can find a link to the forum discussion about it
here. The mod itself is in beta and can be found on the ACE SVN. Currently it takes input from KTM as well as generating its own threat values. It's worth noting that, at the time of writing, these don't feed back to KTM. An interesting point of note it that it can track threat on multiple targets...which is nice.
I've provided an image below (1000 words, and all that).
Points of note are the nice bar under the hunter showing the point at which aggro will be gained (Red Bar), the hunter threat (green bar) and the pet threat (orange bar).
Shows a lot of promise, imo...especially if it makes good on the performance claims. KLH is by far the most CPU intensive mod in Mazzle (AFAIK) and it would be nice to see something like this take its place.