I'm not a big fan of selectable lockers (ARB, OX, ECTED, etc...). First, they are more expensive. And second, I've seen a lot in person as several rigs in our club have all of the above and all have had issues regarding getting them to lock. There is nothing like getting half way into a difficult trail and then being stuck with an open diff. And to be honest, I've never seen any obvious advantages to having a selectable on the TRAIL. On a difficult obstacle where are spinning tires and under power there is no difference in how it works as compared to a Detroit or Lock-right. On easy but just tight and twisty dirt trails I've followed rigs with selectables front and rear in smaller and shorter vehicles...rare that they can make a turn in a single shot and I can't (granted, the Sami's and Willy's have an advantage but it's not because of the lockers).
Some specific examples of rigs in our club.
CJ-7 w/ ARB's front and rear - loses one or both lockers about every 3rd trip
TJ w/ ARB's front and rear - loses one or both lockers almost every trip
YJ w/ front Ox - engages about 1/2 the time at obstacles, usually has to mess with it each time or readjust the cable. If the trail is not too bad he doesn't mess with it and struggles without.
TJ w/ Ox front and rear - same as above. Typically he just gets the rear locked in and leaves it so he doesn't have to mess with it.
TJ w/ ECTED rear - typically just locks it in at the trail head and leaves it alone because it will only engage about 1/2 the time also.