I am in the PNW, so when it rains, IT RAINS, lots of deep puddles and standing water, but its really squirrelly. Might be better with a manual valve body so it wasnt kicking down into first at low speeds. I have been driving various 10 and 11 second street cars for 30 years, and driving a locker with big gears in the rain I am on my toes at all times. The worst is changing lanes to pass a stationary line of traffic, I have gotten crossed up easing into the throttle at low speeds on wet roads many times.
I have absolutely no problem with the locker in mine when its dry, wouldn't trade it for anything. In typical PNW heavy rains, its a COMPLETELY different story.