Running Gemini Defender turrets means there's no downside and the potential for huge upside. You can either place the turrets back-to-back so you get effectively full 360 coverage with increased ammo efficiency, or overlap their firing lines so you have a high damage killzone in a critical area. Hawkeye's increased range mostly means your turrets will fire at enemies too far away to matter. There's the occasional position where it'll get webbers or spitters that the regular turret couldn't reach, but in any situation where you have the 10 seconds to prepare a nest you can build a platform roof to block those sightlines anyway.
Engineer's original weapons might have the most useless mods and overclocks in the entire game. As an example, all the damage mods on the PGL are completely useless because of the way Incendiary works; it'll always set everything less durable than a Guard on fire in the whole AoE no matter how much or little damage it has, and you're always taking Incendiary on the PGL unless you're running either Hyperprop or Fatboy, in which case you're forced to take the armor break or projectile velocity mods respectively. Since Incendiary doesn't care about damage, RJ250 compound is strictly better for general use than every overclock that isn't Hyperprop or Fatboy, which are situational. In total that's 4 dead mods, 1 whole tier that's a completely forced choice based on your overclock, and 3 overclocks that are strictly worse than RJ250. The PGL badly needs a rework simply because there's so little actual choices to be made when building it.