Short answer: it's OP on a a significant number of fights, but not all IMO
It is essentially this. It is a skewed representation of gunslinger DPS. A gunslinger doing 3600 on a combat dummy because dummies provides a perfect scenario of using it does not mean that it will be done the same way in an ops. It's a good tree, but it'd be fallacious to only represent gunslingers by saboteur DPS, considering it's 400~500 DPS higher than the other specs because of one situational move.