I wasn't playing when the stress meccanic was changed, altought I understand why. Running around and punching people with shae was dumb fun, but maybe not how the game is intended. I think however it's not possible to change just the stress mechanic, if I was to ask what is the native's raiders strenght or the wardogs weaknesses the answer is the same, stress management. Just changing the stress made wardog much stronger, while natives are weaker. Let me make you an adectodal example.
I just played "The mouse and the snake", in character selection the rest of my team is Hive, Alicia, Kuzman, this mean I have to go Shae. I'm not the leader altough it's obvious that none of the other player did this mission before (I think this souldn't happend, the leader should be chosed first among the ones who completed the mission). During the mission Hive would chase boss and beholders aound the map, while I have to kill boss and beholders. With the new stress mechanic we draw more or less the same ammount of aggro, but she have 100 hp with regenration, I have only 60, one of the two can ignore the ads the other can't. There was a moment when I get downed by the AoE of the boss, get up, get downed by two random soldiers less than a second later.
I'm fine with the stress changes, but they must be followed by some health changes to, especually with more deadly ads. I think that the natives should at least have 80 hp, even if they had only 100 flat hp with nothing else they would be still the most frail faction, 60 is nothing.