Aargh, forums, broken, can't switch characters. This is Kaels.
Essentially your changes seem to be "I want to turn Druids into Holy Priests". Which I doubt you're going to find much support for doing, since people would just play Holy Priests if they wanted that.
Well, to be honest, if druids were turned into holy priests in the way suggested by the OP, I think I'd be playing a druid. That AoE spell he's suggesting sounds hella fun...that on top of WG? And no more PoH spam? And actual Int-based passive mana regen? I'm sold. Although I think I'd want the AoE to have PoM's sound effect when it bounced. I get lonely without PoM.
While this druid is arguably my main, I have lots of toons that I play regularly, including a priest. He's mostly shadow, though, and I had chalked up most difficulties healing with him to differences in gear. You are not the first person who I've heard debate about wether Sanctuary is worth-while, so maybe that spell needs a buff. Also, make sure you are taking the mana cost I attached to the AOE spell Enliven into account; it costs almost as much as Sanctuary, so anyone trying to spam it wouldn't last very long, and it can't heal the druid who casts it.
You suggested 24% of base mana. Sanc costs 44% of base, or over 9000
On top of that, it does more healing than Sanc, with the numbers you suggested. 500 * 6 targets * 4 ticks * 3 = 36000 healing, before modifiers. Sanc (when not bugged) is 327 * 6 * 9 ticks = 17658 before modifiers, or about half as much.
So basically, your spell heals twice as much as Sanc is intended to heal for half the mana. Of course, in a 25m stack phase right now Sanc heals about 4 times as much as it's supposed to due to lack of diminishing returns, so they're theoretically equal HPS in a situation where 24 people are stacked, except that...well, yours is only splitting its healing among 6 targets at a time/18 total, and the heals are bigger, and they're smart.
Don't get me wrong, I love this spell idea and want it, but it's better than Sanc in every humanly imaginable way.
(I'm talking about your v1.0 idea. I'm somewhat less interested in your v2.0, which just seems...meh. Why would you even want a spell that inefficient and inflexible?)
Also, I acknowledge that the addition of role-specific spells would make druids more powerful healers, and that to keep them balanced there might need to be a decrease in overall healing power, or an increase in mana cost.
What do you think might be a good amount? Possibly a 5% decrease in throughput? A 10% decrease in spell-power scaling? More?
Maybe make all spells 2/5/8% more expensive?
I don't want to invite druid hate, but the forums is a place for discussion, so lets have one.
I'm not sure exactly. I have a hard time asking for nerfs to other classes. What I really want to see is Holy buffed up to your level.Holy needs...well, basically it needs a Revitalize equivalent (Int-based passive regen) in place of Holy Concentration, and Surge of Light needs to be tweaked to proc as much as OOC. And on top of that we need a raid CD and some minor throughput buffs. At that point, we can talk about buffing our toys and maybe giving you some toys too.