No addons in WoW (I assume that's what you're referencing) do what you say they do. At most they give an audio queue telling you to PAY ATTENTION, GET READY TO DO SOMETHING, YOU BETTER KNOW WHAT IT IS. All addons do for healing is make targetting more efficient, which is something this game will need if they want to keep a lot of people interested in the role. While it may not be hard to switch targets, it's damn inefficient to have to click a new target and then cast a heal. But yeah, while I haven't done pvp yet, I did do it in the beta, and targeting was a pain as health bars did not update right away. Maybe it's just my old computer, but still, I would like the issue to be brought up.