I've used Grid for some time as it became a great way to monitor raid status information as a raid leader with minimal screen real estate.
Although I used it for healing small groups and PVP when the time came, I never spent much time configuring it and thus didn't realize exactly what it was capable of. I spent a few hours recently messing with it and found some extremely useful features and modifications that can be made to turn Grid into a near-fully functional raid frames for healing roles.
The best part about using Grid in this way is it allows me to focus a lot more on my surroundings as a healer in stressful situations, rather than looking at multiple places on my UI to find relevant information to the raid's overall health and my heals as well as the heals around me. I'd love to see a thread on here where everyone posts their UI in various forms just to see what others are doing (and maybe I'll start that thread up). In the meantime, I'll offer up my moderate experiences with Grid and how I've configured it to be exceptionally efficient as a healing Druid in a raid setting.
I've attached four screenshots, and they all just show different "states" of action for Grid so those of you that have never used it can see the basics. The last shot is just a scaled up version to make sure you can see things clearly.
My Grid Settings
The main box background for each raid member acts simply as a health bar, as is standard. The bottom bar is a mana bar (can be set to show energy/rage as well, though I have little use for that information and disabled it).
The texts are pretty simple. Obviously name is the first, and the second is actually customized for me as a Druid. It shows the current Lifebloom stack duration timer on that player, counting down. It's also customizable in things like color/size to indicate various stack counts. I used something I could easily remember, so as with a traffic light, red indicates one stack of Lifebloom, yellow two, and green is a full three-stack. The second attachment, as you can see, has Kulldon with a fresh 3 stack and Kulldam with a single stack.
Aside from texts, Grid also shows vital information with "status icons." These are generally colored boxes used to indicate something within a particular member's frame.
In my setup, I use the top three icons (top left corner, top middle, top right) to indicate my heals on the target. Top left shows if the target has one of my Rejuvs, top middle shows if target has Lifebloom (and is again color coded like the lifebloom timer below), and top right for my Regrowth.
Another very handy icon (which you can't see here) I use for the right side Icon, and that indicates if the player has incoming heals to them. This is very handy in a raid to prevent overhealing in non-tank heal situations. If the player is about to be healed, the status icon appears.
Other status icons I use include: Agro, death, other healers' Heal over Times, and others
Lastly, although it's not apparent in these shots, another great feature of Grid is it all but eliminates the need for a decurs mod frame (such as Decursive frames) as it performs the same functionality but keeps it within your raid frames. Grid has a priority system to and will display debuff icons on the center of a member box based on what they may be afflicted with and it's priority.
For my Druid, I have Poisons and Curses first priority of course. I also have it set to show missing buffs I can cast on raid members when out of combat (Mark of the Wild) which eliminates the need for another mod I used for that purpose called RaidStatus.
As with most mods, Grid can't do everything, but I'd highly recommend it to healers that from time to time get frustrated by the number of locations they have to monitor for efficient healing, or simply healers who want to try something new.
On another note, I'd like to hear about (and see examples of if possible) other addons that healers find useful in raid/group situations, so please share if you've got anything.