You already have a rear e-locker as standard. As far as adding a front-locker, I really don't think that measure is going to make or break the difference in your having been stuck.
The traction control system does a pretty good job of making sure you don't blow all your drive into one wheel. It doesn't work quite as well as a locker, but it's about 70% as good. Bottom line: I doubt it'll make that stuck or not-stuck difference.
Check out V-bar ice-breaker tire chains. My buddy Mark runs a set on both his front & rear tires for ultimate un-stoppability. If conditions are that bad you'll want the chains for traction when applying the brakes: for all as tough as our 4x4 systems are, they'll do ya no good when it comes time to stop. Your money is better spent on a winch and some extra tow straps.
The front-locker is something I recommend only for the hardcore off-road enthusiast. Or people in San Diego who need to substitute gizmo's for talent
