Psi ops are crazy powerful, but should be used with care I noticed. I have had one on training for a while, got a speed boost as well I think because it suddenly took very little time to upgrade some abilities. Including the one where you get extra turns per squad member in proximity, but I wasn't sure how that worked.
Got a mission, set up an overwatch trap on a group of 3 and pulled with the void ae ability. Psi op then proceeded to kill all enemies activating all its abilities. They didn't even get to do their move animations for spotting me.
Not that good when wasted on trash, especially when you can't control the abilities the ops uses and causes all of them go on cooldowns, but can see it saving the day when fighting a boss or something similar.
EDIT: I alt tabbed to write that, I just noticed that none of the abilities used are on cooldown except the first one I used to pull. That seems OP. Theoretically if you put 2 psi ops together with the proximity skill with the rest of the squad, you can do 1 initial + 5 from proximity, so 12 attacks from two people? That can't be right.