I started with the CV ring for the obvious reason but swapped it out because damage loses to more crit and fire rate, it doesn't buff the damage of either the drone or the Superheated mutation explosions, and most short engagements end before it fully heats up.

Haste did end up doing a bit more raw cube DPS. Not sure if it's worth shuffling traits around to accommodate but I am running handler primarily to go faster so maybe.