I think they should develop their own, unique psychological profile and 'duster dementia.'
If CCP just decides to go with PTS, I'm sure we can come up with something better.
Hmm. Well, "capsuleer dementia" (which I swear to the divinity of your choice I didn't invent) is based on observable behavior by capsuleer player characters, both "immersionist" and not.
It's pretty obvious.
DUST mercs are inevitably going to be a little more subtle. The people who don't really "get into it" are probably those who will move on to something else soon enough, while I suspect those who stick around will mostly be members of standing corporations. The more successful ones are apt to act in a manner that would nearly be reasonable for an RL soldier under similar circumstances.
What's really going to be telling is how DUST mercs (myself very much included) interact in practice with PvE elements. If CCP gives us destructible apartment buildings, will we destroy them? If it gives us enemy soldiers, do we insist on wiping everybody out, or do we just get the job done and go home?
How willing are we to die in order to give our teams a momentary advantage? (I already do this, often-- it's amazing how many people you can drive insane with bloodlust by wearing a scout suit and running right through their lines, bobbing and weaving like mad. Every hostile you draw off is someone who isn't killing your team or providing meaningful support to their own for as long as you survive.) How willing are we to slaughter pointlessly?
It's entirely possible that DUST soldiers (I'm sure Aria will have a thousand theories why) will be crazy in much less alienating ways than capsuleers-- more prone to reckless disregard for their own lives, less prone to reckless disregard for others'. And wouldn't that be interesting?
I really don't see the major issue here - "When hurting, eat gun?" - assuming your in a condition to do so, the only thing a pain-averse Dustie should fear would be a situation where he/she was wounded to the point of being unable to self-terminate, assuming there is not some mentally activatable kill-switch you can flip to end it and return in a fresh run.
When death is meaningless, the only remaining scare-factor is immense pain, and assuming most infantry weapons and vehicle-mounted ordinance is highly effective at it's task, the situations where you last for a bit should be quite few. Even then there is the potential way out?
DUST troops can suicide at will. That's not really the issue. The issue is mid- to long-term mental health. You don't have to lie there and slowly bleed out, but you do experience the traumatic injury that has you bleeding out in the first place. It's one of those situations where, if you're lucky, you just got pulped or your head got blown off.
If you're unlucky, you're suffering a deep puncture from a rail flechette, mitigated somewhat by your suit's now-breached armor matrix. If it hadn't been partially stopped, the kinetic energy would have torn you neatly apart. As it is, it's just splintered one of your ribs and ruptured a couple of your favorite organs.
Owie.
Even if you bail out, that's a bad moment.
Edit:
Also, there's the drop uplink, the short-range wormhole generator. Using it results in agony, followed in short-ish order by cellular (or something) degeneration and death. THAT has got to be an experience and a half: every nerve in your body reporting not only spatial warping but also that at least some of it wasn't put back together quite right.
Jayne offers a bit more than just pain, Creep.
("Pain is scary" is his line in that scene.)
Oh.
Well, I guess I've failed to keep my Firefly quotes properly memorized. Must remember to rewatch (though it always makes me sad).