This won't really be new info for many people but I thought I would add my experiences to the pile. I'll be focusing on AST since I don't think anyone is disputing that WHM is in a very good spot right now.
Background
For those that don't know, AST's core healing kit is basically this: Benefic (cure/physick), Benefic 2 (cure II), and Helios (medica).
What sets AST apart is Aspected Benefic and Aspected Helios. In Diurnal stance, AB is similar to WHM's Regen, but front loaded. AH is similar to medica 2, though notably shorter ranged.
In nocturnal stance, AB functions as adlo and AH as succor -- but notably, compared to SCH, it retains spammable Benefic 2 for stronger single target heals (nocturnal stance's potency boost brings it pretty much in line) and Helios for spammable AoE -- ie, still a medica of sources.
Benefic, Benefic II, Helios, and Aspected Helios cost a little less MP than WHM's counterparts. Aspected Benefic is a little more expensive than regen, but much cheaper than Adlo. Luminiferous Aether, the MP recovery ability, has the exact same potency and duration as Shroud of Saints
Lastly, AST has a single "emergency" heal called Essential Dignity -- oGCD, 40 second cooldown, and only 400 base potency but this scales up as the target's HP decreases. In my own experience, it's an almost-full heal for low HP DPS.
Healing Comparison
I took both jobs to the level 60 dungeons at i166 with i170 weapons -- decently hard hitting mob packs and bosses. I did not take AST to EX primals as, after my experiences in the current dungeons...I did not feel up to healing harder content on it
For the dungeons, I would call AST's heals "sufficient." They can get the party through, and the mix of AoE and single target provides enough tools to get the basic job done. The main difference, I noticed, is that on AST I'm letting party members sit at low HP for a lot longer. If there is any complication -- DPS getting paralyzed by the Curator's mines, or the tank eating vulnerability stacks -- I found it was considerably harder to recover this on AST, and far worse for my MP pool.
I do not feel that Collective Unconscious is as bad some people make it out to be, at least in Diurnal Sect. Throw up HoTs before using it and it's some fairly potent healing. In Nocturnal Sect... I have a hard time seeing it used outside of a new Nerve Cloud mechanic, where all damage stops and then there's a very huge raidwide hit.
Mobility
Now here is what AST is good at. People knock on Diurnal Sect's 5% speed boost, but this lets the caster stutter step just that much faster -- and you don't need to stop at all if you get the Enhanced Benefic proc or, if you want to completely run and gun, pop Lightspeed.
The problem is this is a bit situational. It could have utility in Turn 12-like fights, or while learning something like Titan EX. However, outside of those circumstances, this is not particularly an advantage while retaining the downsides.
Also, WHM has gained a number of oGCD instant healing abilities now, strengthening its own mobility a bit and SCH has never really hurt that much from moving.
MP management
Ok... I've got to be honest. AST sucks at this. It's really bad. I try very much to make every spellcast count -- to get every last hp from every heal to mean something, to spend the absolute minimum MP I can to get others' health up... and I still run out. I start to panic when I see my MP reserves approaching their end and hope the DPS really gets a move on finishing it.
By the way, it's worth mentioning that even if I have the GCDs to DPS, I don't usually have the MP to spare.
Same boss (Curator), same tank, on WHM I can end it at 100% MP (no DPSing for comparison) and generally it feels much less stressful.
Numbers-wise I have a hard time pinning this down. Cure is very close to Benefic to HP restored and Benefic is actually slightly cheaper for MP, etc etc.
Mitigation and Buffs!
Ironically, in Diurnal Sect, I feel WHM has better mitigation than AST. E4E is pretty powerful, Stoneskin isn't what it was but it's not gone, and WHM Virus is still useful for those bigger physical attacks...and notably, it lasts a duration, while AST's disable affects just 1 attack (hard to use on anything without a cast time...).
Nocturnal Sect makes up for this a little, but at the cost of HoTs. I've mostly been focused on Diurnal Sect, so I'll leave AST's mitigation in Nocturnal to others' evaluation.
AST, however, has some very nice buffs. Although subject to some criticisms, if these buffs are landed at the right moment... for example, Spear just before a MCH/BRD blows all their cooldowns, Balance on a SMN about to go ham on Dreadwyrm Trance, Arrow on melee DPS generally -- it seems these can be pretty powerful.
The catch is setup -- it can take 1m+, if RNG is in your favor. If it's not, you might not get anything actually useful to the party for, well, who knows long. I feel this works better on trash phases with downtime, but feels harsher on bosses and hard-mode primals with a lot of uptime.
But my biggest criticism of cards is this. It feels bolted on. It feels like SE took a subset of WHM's core healing spells and then just threw cards on top of that. I wish cards were more central to AST's gameplay somehow. Instead, it's "play redressed WHM with 2 skills that feel a bit SCHly in the other stance, and every now and then do something with cards."
I'm not going to offer suggestions since I'm posting this as an evaluation.
Style and Aesthetics
This is very much an opinion but... I love everything about AST here. Celestial Opposition is easily my favorite effect in the game. The poses/animations, sound effects, the weapons -- everything generally, very well done. I love all of it. I want to play AST for this alone. WHM is flashy, but for style, AST is hands down superior for me.
Raid Viability -- AKA, Is It Worth It?
AST buffs are nice... but subject to RNG. Now, is it worth it? Here is what I think raid groups can anticipate in bringing in AST:
* More load on the other healer (less DPS time)
* Need for additional Mage's Ballad/Bishop Turret Support-Mode uptime
* Potentially less burst healing capability (depending on the other healers' capabilities)
My personal thoughts... I might take AST in to Alex a few times just to experiment, but I worry that (compared to WHM) it would just make it harder on my group for benefit I'm not too sure of.
If anyone has both SCH and AST to 60, and had time to play around with both, I would love to hear your thoughts.
EDIT:
MP Usage Revisited
Here is a post from reddit user glasswings that goes deeper into the theorycrafting behind AST's MP usage and recovery, compared to both SCH and WHM.
http://www.reddit.com/r/ffxiv/commen...ain_astwhmsch/