If you want a POW situation then you got to make it fun for the prisoner, as well as being a disincentive. So how about:
You get locked up, (the enemy has to take your backpack to a holding cell) you lose 50% exp and you get removed from your squad, making it a pain in the arse if you do become a POW.
Once there, you are equipped with a Rek, pistol and infil suit. If it's unguarded, no problem, off you go and hack your way out. If it's guarded you have to either fight or use stealth. To stop spawn killing, the guards can only kill once you are out of the compound, however, they can 'capture' you and you get put back in the cell. Make the holding cell full of corridors and hiding places, so it's a kind of Metal Gear Solid experience.
Just an idea, some good, some bad, needs work.....
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