As a tac who often PUGs I almost always stealth, I'd prefer to not to but a good stealth and a bad stealth are different things. I can kill the close left, far left and far right 4 out of 5 times without agroing any of the mobs. The close right is a run for your life situation.. I avoid that.
It completely amazes me watching idiots run around the room shooting turrets and other random enemies and then walking right by the saboteurs because they aren't shooting back... unbelievable. These are the same people that bolt into an area in round 2 and start the timer off in round 3 with 2 people still dead.