I daily drove a Jeep with a spooled rearend for 2. 5 years. Not pleasant, but liveable, since in my mind, it was an offroad toy first and a daily driver second. And it's worse in a short-wheelbase, flexible suspension vehicle (lots of sway going around low-speed corners) like a Jeep than it would be in a truck. Wet traction was tons better, IMO, than a Detroit or Lockrite, both of which I also ran for awhile at different points in the Jeep's evolution.
With the spool in the rain, it always pushed going around corners, which was a pain in the rear, but at least it was predictable - no sudden lockups in the pouring rain getting on the freeway like I saw with auto lockers! It would be okay in a truck, but if you like having a nice, fun-to-drive, comfortable street vehicle, and/or put a lot of miles on it every year, I'd go with a selectable locker...
Chris