I kind of like the electric lockers. I'll give you my opinion on each type though.
ARB's have had their own problems over the years. The biggest problem back then was the solenoids failing. They're still susceptible but they seem to last longer then before. The earlier ARB's came with C-clip eliminators which was really cool. Then they redesigned it so it would work wit the C-clips. One of the biggest problems with the ARB is if you're housing is out of spec. It can have a very slight bend to it and this would cause it to grenade a ARB. The D35 flexes quite a bit actually. ARB's have also had problems with oil getting into the air lines. They fixed this with later models I believe.
You're also dealing with air. You'll need a compressor that will run the ARB. This complicates the system and adds to the cost. The air lines can snag and crack if you're not careful, too. Although, you could buy the braided stainless steel lines or you could sleeve the regular lines with clear tubing. In any case you're dealing with electronics, pneumatics and mechanic systems which is a lot.
OX is the only cable locker on the market. They were going to have an electric version but I guess they ran into problems. OX is supported by Drivetrain Direct which I believe is owned by Superior. The first problems people usually run into is adjusting the shifter correctly. It takes a while to get it right.
The cable requires you to drill holes though the floor to mount it so if you don't like drilling large holes, you might need to get someone elese to do it for you. Routing can be tricky in that you don't want it to snag or become a limiting strap for your suspension. Another down side to the OX is that it uses a custom diff cover which holds the cable in place. This can be a problem if you like to run into things with your diffs. Protecting them, would require something custom built.
Electric lockers have been around for a while. Toyota has been using them with their trucks for years. About as long as ARB's and Detroits have been around. Only now has the aftermarket jumped on the bandwagon. Electric lockers are a bit simplier but you're still dealing with electroncs. There is a actuator at the diff, the a relay with wire rumming from the dash and battery. The Tractech electric true-trac is interesting in that it is a LSD that locks up rather then an open-differential. The down side with their design is that the actuator is built into the housing and is rather big.
Eaton got around this by putting everything inside the differential. The only requirement is to pass a wire through the housing. This is usually done by passing the wire under the diffcover and using more RTV gasket. Routing is still key like with the ARB and OX.
Honestly, each locker has it's own pro's and cons. ARB's have had problems but they've also been around the longest and have worked most of them out. OX, isn't that new but they almost went under until DTD/Superior helped them out. Tractech has made the Detroit and True-Trac for many years, the Electric locker is new but I haven't heard of any problems with them. Eaton is also new but again, they've used their years of knowlage of building axles and differentials to design this locker. Haven't heard of any problems with them either.
If I was going to replace my Detroit, I'd probably go with an Eaton or ARB. I already have OBA so I wouldn't need to buy their compressor.
Oh and another thing, if you're on stock axles, you might want to consider upgrading now rather then later. You will never recoupe the money spent.
