Nice post, as always, Aliena.
I like to use Mikscrolling battle text, if only because I already use it for my other characters. It's significantly less useful for healers, which is probably why you didn't mention it, but it's always nice to be able to glance at the scrolling heals and see what they're currently healing for. It's also useful for cleaner, customizable fields in which you can see the damage you might be taking and the buffs or debuffs that might be stacking. It can do a lot more, but I've found that most of the other things it can do are covered by addons such as Power Auras or not needed for healing.
But, Raid Frames, Unit Frames, Cast Bars, Bar Mods, Boss Mods and Buff/Debuff trackers are certainly an encompassing base for any healer.