I have been programming a DK simulator for quite a while now which is quite different to rawr in that what I am doing is reversing alot of calculations I have this gear what spec best suits it. DK's have some of the wildest talents and what the sim does is attempt alter talents to cover shortcomings in gear.
So if my gear is say lacking in threat stats a slightly higher threat build may actually work better than a straight survival based spec. What I end up with is a 3 axis graph EH(survival) vs Threat vs Mitigation.
The tricky part is weighting them so you can resolve the 3 spline equations :-)
For threat for example if you go below 5K TPS it uses a log table of the diffence as you will have huge issues and similarly once you get above 12K TPS threat weights in inverse log.
EH is nice and linear but mitigation is a nightmare and took ages.
Results look promising so far but I need more data and TIME!!!!!!
It sort of the opposite to what you are doing as well as you have a DK represented on a single line I would have multiple lines depending on what talents they had in or out. I understand that at the end of the day you end up with a HP and and armor value which you are using but those values are also changable by talents and those talents have other effects as well.
** Remember Warcraft players fail in directions you never thought possible.