Ill start off by saying Im not defending all the changes to SMN because I dont agree with alot of the changes, simply cause some of them come off as clunky, such as.
Being able to activate aetherflow even if you already have max aethertrail stacks. This essentially results in a wasted aetherflow and a major set back in dps.
On the same topic, not being able to aetherflow while you are using dreadwyrm feels odd, and it means you have to wait for dread to end before using aether flow again, meaning you lose out on precious seconds of cool down time.
No sustain, it does have its purpose.
Aether pact feels slow and doesnt always work.
And all the nerfs to aoe seems excessive compared to my blm friend, plus with the removal of blizz II, there is NOTHING to do during aoe heavy dungeon runs after your dots are baned and shadow flare applied other then throw out single target dps or a painflare, spamming ruin during dreadwyrm when there is 9 enemies in the pull makes me feel like I'm not doin anything.
BUT while everyone here seems to be completely focused on the negative changes there are some finer details that improve SMN DPS and compensate for alot of these nerfs that nobody seems to be talking about.
For instance:
Dreadwyrm resets tri-disaster, done right I've only found myself casting dots once every couple minutes.
Not only are DOT application instant when using tri, but the change from 3 dots to 2 means less time applying 3 dots, and thus freeing up 1 global cool down for ruinl-lV when you actually have to apply dots manually. It also shifts smn away from relying heavily on a dot tick for dmg and just putting some of that more directly on the enemy through a ruin.
Tri applies ruination, increasing potency of ruins by 20 for 15 seconds, so since you are spamming ruin III mostly during dreadwyrm anyway it's 170 potency when it counts, they also compensated with the addition of ruin IV which can potentially be thrown out for almost no mp even when you aren't in dreadwyrm, on top of that ruin base potency is 80->100, so there is also 20 more potency there aswell.
Contagion, 10% more magic damage FOR EVERYONE. Since smn no longer needs to reapply dots manually as much, this change is big, this makes everything casters do better and for those unaware Foe req is no longer a thing for casters, it's 3% dmg for everyone and battle voice doesn't effect it, so contagion adding 10% dmg for casters and healers to capitalize on is a decent increase.
Shadow flare was made a cool down, while technically a dps loss in the long run, it condensed all the dps into 15 seconds instead of 30 so you had a better chance of getting it's full potency, also since it's a CD you get that extra ruin in again instead of casting shadow flare.
So from my experience SMN can hold their own with other DPS just fine, the true problem is how HARD it is to get good potential out of SMN.
In comparison, managing dots, aetherflow/trail/demi bahamut, ruin IV procs, tri disaster cool downs, Enkindle, ruination, contagion, and your pets position and health is alot more daunting then your typical rdm rotation, smn is far more punishing if you mess up and they have to stay really on top of their game just to stay on the same level as rdm.