We got a 2001 frontier crew cab with the off road package a month ago. I just had my first chance at using the 4wd. I was headed up for a spring bear hunt. I'm hunting only about 12 miles from my house so coming home every night. Anyway, it wasn't anything major, but did include a creek crossing and some very steep ascents and descents in 4 low. I was very impressed with this thing. Very smooth ride, smooth shifting between 2wd, 4wd, and 4 low. This truck has the automatic, which is a first for me in a truck. It has a limited slip and it seemed to be doing it's job. Anyway thought I'd share we love this truck. Hunting is about the only time I get it, the wife loves it too.
I throw the switch and lock the diff in mine every once in a while, but have never really needed to. Sometimes the light just flashes and it doesn't engage anyway.
__________________ 2005 Frontier Nismo CC 4x2 -- Aztec Red, Rockford-Fosgate, Sunroof, Side Curtain Air Bags, Tow Package, Bed Extender, Hard Tonneau (finally!!), Microfilter, Manik Step Bars, Nissan iPod Interface, Ground Wire Kit, and more to come . . .
I've had mine almost a year and have hit some trails here (muddy and gravel) haven't needed 4L and haven't gotten stuck yet. i'm waiting for some new tires so i can hit the trails again.