I have a confession...I've been healing using the default party/raid frames..
They are alright - much much better than they used to be. I am using mouseover macros along with them, but they have serious limitations -
---only shows 3 buffs max, but Resto can do much, much more than that - 2 Rejuvs + Wild Growth is already at the limit. You can also have Cultivation, Regrowth HoT, Cenarion Ward, Stonebark, and Lifebloom, among other things.
---Not really that customizable - I prefer my 5 man bars horizontal, but the defaults seem to only be vertical
I also plan on getting ElvUI tomorrow as my UI in general is a mess. Does ElvUI come with stock servicable raid frames? If not, how about Grid, VuhDo, or others? I've heard good things from all of them.