I came to this forum just to discuss the OP-ness of turrets. My build that absolutely ROLLED hard (and would handle even harder difficulties with ease) called for one ninja exo, specced to turrets (with a minor in stealth actions), one science exo, specced to radar range and hacking (with a minor in viruses), and a siege exo specced to having lots and lots of shadow torpedos.
Now, I was playing with Genji 'cause I like my exos epic. But this was my second serious playthrough and I ended up curbstomping the game. As I got up to 40-50 radar range and 20+ trap skill (eventually reaching 130 or something), every mission I'd just drop a few turrets in the entry zone, swap to my science exo to get sensor readings, use the siege to blow up doors (Yeah. I used shadow torpedoes to blow up DOORS from the spawn point), and whistle in most of the level to my turrets.
Who would then proceed to massacre everything. Lion's Den missions, assassination runs, bot command centers, you name it. My turrets would one-shot most things, with tough things taking at most ~5 shots. Some bosses were kinda tough. After the main brunt was cleared out, I'd go in with a sniper exo or the rockets on the sieger to clear out those oddbots who don't path right, and if I saw anything scary I'd just whistle and scarper back to my mommy turrets. Or drop some more, since I was carting around plenty and never needed all of them.
Let me put it this way: I ran the numbers. My ninja had over 12,000,000 in potential damage by endgame. If I'd played differently (by playing out the endgame slowly, trying to boost trap level even higher) and perhaps started with a second ninja exo, I might have been able to kill a murderbot. Just outright kill him. They've got 100,000,000 health and are supposed to be "unkillable."
So as much as I hate to say it, turrets are kinda mad op, yo.
Oh, and my final mission... I almost lost. Almost. Teleporters were a new concept and I hadn't fully figured out tactics vis-a-vis them and that cost me a couple good bots, plus something about that mission (either the teleporters or the human reactors) was really screwing with AI pathing. Like they'd dance around at a corner, unable to decide if they wanted to come at me or the reactor. So that made the whole "sit and wait" plan less good. But eventully I managed to clear it on day one, with two barely-specced bots.