Thanks for the insightful post. Gave you +1 rep.
I'm relatively new to DDO (although not to MMOs) and my main is a level 14 multiclass with 11 cleric/2 monk/1 rogue. Basically it's following the Valiance build, except I took Empower Healing instead of Empower Spell so I could get the radiant servant enhancements and its healing aura.
The reason I chose this build is because of work and family commitments (I have 2 little girls aged 4yrs and 8months). I needed something solo friendly since playtime can be sporadic. However as I gain higher levels, I find myself grouping more and more. I realized that most groups will be 100% happy with a healbot that chugs pots... or whatever they have to do... to keep them buffed and healed by standing in back and casting heals and buffs only. However that's not how I want to play.
I don't have great gear just yet, but I believe I'm most similar to Cleric #5 from your list. I don't care what anyone else says, it's my job to help the group accomplish the quest/raid objectives. Usually that means keeping party members on their feet instead of in my backpack (though not always).
I had a great revelation of this last night while running a quest with some guildies and some pugs we got to fill out the group. It was the first time I was running this quest, and at one point, our leader gathered us at a doorway and instructed us to wait. He then pulled 4 baddies (can't remember what type now, but they hit hard) back to the group. Well they did hit hard enough that the group needed healing, so I used the best mass heal I have available to me at the moment, which was mass cure moderate wounds. Each time I cast it with empower healing enabled, it costs me 70 SP. I had to cast it three times before we were done killing just those four baddies.
So when the leader ran ahead to pull more, I decided to go to the other side of the doorway from the group, and watched for when the leader was returning with the mob. When I saw him returning, I cast blade barrier, which costs me 70 SP with maximize/extend. On the way back to our group, he had to pull the mobs through both sides of the blade barrier, which reduced the mobs total HP by about 40-50%. The fighters were then able to easily finish the mob off without needing a single heal. My radiant servant I healing aura was sufficient.
Lesson learned: when I stood back and only healed, I burned up 210 SP (out of my total 825 SP). However when I utilized a well placed blade barrier, I only had to burn 70 SP and didn't have to cast a single heal. Meaning I served the group in the most efficient manner possible.
Now I can't wait until I get to level 20 and start collecting good end-game gear. I'd love to be able to take aggro and kite mobs through my blade barriers... regardless of what the fighters are doing. They just want to stand there and swing their swords anyway, so what will they care?
For now, since I don't have the gear or abilities to do that effectively, I'll just continue looking for ways to maximize my support role based on the capabilities I do have atm. If that means throwing up a BB, or casting Greater Command, or buffing my party with deathward instead of casting restoration a bunch of times, then that's what I'll be looking to do.