So you say the Atrac allows 1 wheel to spin , which even if you didn't have it you would only have 1 wheel per axle spinning.
I was out testing at the beginning of december and trying to hill climb in a foot of snow using different mode of 4wd. In doing so we were really giving it hell after stopping half way up the hill, and trying to restart our climb up. Why then was I able to have all 4 wheels roosting snow ( as per my spotter ) . I thought it was my Atrac working since it applies slight brake pressure to the one wheel to help get the traction to the other wheel so both spin.
I've had a locking rear diff in my Tahoe ( 04 z71 ) . It was the type that did it automatically , not by a specific switch. ( atleast GM called it a locking rear diff. ) It worked well.
In my Ford truck ( f150 crew cab ) they were spec'd out as having a limited slip rear end. It also worked well.
Both had front open diff's so in reality it was 3 wheel drive in a snow / off road situation when traction was being lost.
I know with the Tacoma you can get 2 different types of set ups . Either a rear electronic locker ( works in 4lo only ) or a automatic limited slip ( works in 2wd , 4hi & 4lo ) .
I think for 99% of the people the limited slip diff is a better choice for on and of road situations. My friends Tacoma with the off road package has the locker. Because of 99% of the situations he encounters the locker is useless unless he is doing some real heavy crawling.
Ideally I would love to have true electronic lockers in both front and rear,but its not very practical IMO.
Toyota Atrac is building quite a name for itself in off roading and off road racing. It must be a good system. And probably a wave of the future type of axles to come for the average off road person. Rock crawling,mud bogging being the exception.
Please correct me if I am wrong in my thinking .... always need to learn , so I can do more testing.
