Hey Seth, here is my limited knowledge 2 cents. i put a powertrax no-slip in my rearend, it works great and made a tremendous difference off road. it doesnt chirp when i turn unless i give some gas then it locks up. the next year we put an arb airlocker in the front. it made a big difference especially when crawling over an obstacle. all this said, if i was to do it all again i would have saved up the money and put in an air locker in the rear then when ever i could scrape the money up put another in the front. slickness is the issue, if snow covered or ice covered roads i'm not going. i've been caught a few times by a snowstorm coming home and it takes the fun out. probably the worst thing is a side hill on the trail when you're just in rear wheel drive . we were in the tobacco roots a couple years ago see how far we could get. had a spot that snowmelt was crossing the road and didn't think anything about it. when both wheels lock up there's nothing to keep gravity from doing it's thing and the next thing i knew i was pointing into the hill. luckily the berm was frozen enough i stayed on the road, the guy behind me thought it was the coolest thing he'd seen.
so after all this rambling i wish i'd waited and put in a user selectable locker in the rear and glad i did wait on the front. one other thing is that i don't use 4wd as often as i should because ididn't think i needed it. tire wear difference is noticible, perhaps it's because i usually have my travel trailer behind me so it pulls harder but i have started using 4wd again like before i had the locker. saves a lot of tire wear