What if.....

You make 2 keymaps in ISBoxer:
1 with 2 steps
the other with 1 step

On the first dps burst macro you use press hotkey for exorcism on keyrelease, because if you run, and you dont get a proc, you simply cant cast excorcism because you are running and it will interrupt the spellcasting.

The second macro is the same as the first, but you remove the second step, this is because if your in Frost Nova for example, your not casting excorcism? Might be an idea.

I remember on lvl 80 i met 4 ret paladins, and only with holy shock the guy brought me below 40% hp on my main char.