LKincheloe(see: The Mixup Engie/Conch).
On that topic, I'm happy to see the Conch is whitelisted. I'm really hoping to see pockets start using it more often. Harder to protect the medic without a shotgun, but perhaps keep a scout around the combo. That may give up some flank, but would give them the ability to bust through chokepoints/holds with a popped conch. /theorycraft
As for the Quick-fix, I feel like its in a real limbo as a weapon itself. I feel like any nerf to it (remove the half overheal for example) would instantly put it in the same category as the Vaccinator (Side note, Valve please fix this gun, its too much fun to suck) and no one would even think about using it.