Yeah, as Wugan said, I wouldn't be too quick to dismiss it. I believe torparse is using threat as a way to compute effective healing, and it seems to be working rather well. The difficulty just comes from the talents that reduce threat as well as Guard, but I believe you can readily discern whether or not the talents are in effect as well as whether or not Guard is in effect simply by observing the heal numbers. There will be enough "full heals" that you'd be able to determine the modifier for each individual.
Thanks, I'll certainly take a look at that before we decide on a course and may end up doing a blending of the two modes. After my research I'll post the findings.