That is not really why Regen was nerfed, nor was IH being a toggle what overpowered it. Regen being an issue in PvP was more due to perma MoG than IH being overpowered. Prior to ED, you could 6 slot all heals and with the ability to stack Dull Pain, you were essentially unkillable. We had a Spines/Regen scrapper back in the day who would tank Hami for us. What most fail to mention is that in building this way, your offense was next to nothing.
At this point, as much as I would like to see IH turned back into a toggle, I have to agree with those who suggest rolling /WP instead.