I personally prefer the Vestal heals steady and reliable. Sure, Occultist heals have the potential to be awesome... but it also can also fail you. But, I reckon you can get trinkets that lowers chance to land bleed and/or +bleed resists on the others.
Mind you, I have not upgraded an Occultist yet. The concept of basing my heals entirely on the whims of RNG is not something I can fully support.
I feel that basing your strategy on stun-lock parties severely limits your options. There are enemies that have high stun resistance, so it can become a liability if your stun-lock party can't properly fight without the main tactic.
Though, I guess you would have some luck with other strategies once you begin to gear your people at the blacksmith/trainers...
I personally advocate brute force with a smattering of bleed/blight/AOE when opportune.
Beware of relying on A Teams. Sometimes your heroes might leave (for good? I dunno). I just had one of my favorite bandits (not superDismas, thank Nyarlathothep) leave "looking for a vision" after I left him meditating in the abbey to de-stress him. After seeing this I think cycling characters is even MORE important, as to have something decent to fall back on if this (or dungeon death) happens, instead of raw noobs.
From my experience, they come back, eventually... as long as there is still room in the roster for them to come back.
And yea, your A team shouldn't just be 4 characters anyways... since they will eventually outlevel dungeons and you'll need to train up another team if you missed a boss or find that there is an awesome trinket reward...
EDIT:
For stress management, if you kill something with bleed/blight, noone heals any stress. But, its a payoff in the end if you want to avoid further damage/stress.