I like the E-locker since you can easily fix the actuating wires out on the trail if it gets ripped off.
It happened me a wile back, but all I had to do was strip the wires some, twist them together, and isolate it with some duct tape.
It's hard to do that with an air line...
And it still works, so I havent bothered to fix it properly yet...
I was a little suspicious regarding the design at first, since in theory it seems like it would disengage for a fraction of a turn
when you change the direction between forward and reverse.
But I haven't notived it in real life, I don't think it will disengage as long as it's under load...

I've done a lot of rocking back and forth under throttle with the diff engaged, and if it would have disengaged,
I think something would have broke when it re-engaged again...
BUT if I already had onboard air, I think I would have choosen the ARB instead.
Mostly because of it's reputation.