As of U12, Abbot's health:
Normal: 135k
Hard: 209k
Elite: 303k
Credit belongs to Vanshilar for determining the HP.
Before U12, arcanes could contribute somewhat to damage. The Abbot now has Evasion with a pretty good reflex save, making Delayed Blast Fireball and Meteor Swarm not worth casting at him. Arcanes were already gimp enough since he's immune to electricity and cold, and there aren't enough acid spells to justify those enhancements. Now they are relegated to waving wands for inferno, and keeping the trash mobs off the healers. Arcanes now stack poorly against the Abbot. You don't want to bring more than one, and you can do just fine without one at all. Has Turbine learned nothing about class stacking from other MMOs? Go do some research about EverQuest where this was a huge problem with Enchanters, and how it was addressed.
Artificer's ranged piercing damage is gimp against Abbot's blunt DR. The triple positive heavy repeater I crafted is a complete waste, and the homonculous is more of a detriment from dying compared to any benefit it brings.
If you aren't bringing a divine or a monk to Abbot, then you're a drain on this raid. I could almost accept that if the loot was BtA instead of BtC, but it's not. Monks have the best damage profile with unarmed attacks and they bring Evasion as well, letting the divines focus on keeping Divine Punishment stacks up instead of healing.
Pre-U10 when they Abbot had 50k health on elite, he absolutely needed adjusting upwards. U11 bumped Abbot to 135k HP for all difficulties. However with U12's changes the Abbot is way overtuned. All the well known and frequently successful pug Abbot raids on Orien have dried up. None of them are completing now.