I have a No-Slip (Powertrax) in my 2000 XJ.
Ive had the locker for about 5 months. I don't care for it. There is too much play in it driving on the road. When I start accelerating from a complete stop (going straight from a stop sign), sometimes one axle in the rear doesnt kick in. When the other axle kicks in after a second or two there is a loud pop. This may just be a sacrifice that I have to deal with, but I would rather get a detroit full carrier locker and deal with sqealing around corners and fast loss of tread. However, I have never had a problem with it off road. Both axles always turn fine in low range. So far, I have found the powertrax locker to be a weak system but it hasn't given up yet. Mabey it won't. when I bought it, I thought I was a getting a locker that would be comfortable on the road but it hasn't been.
My advice would be to go for the detroit. Though its a bit more expensive, if your really into off-roading like myself, spending a couple hundred dollars more now might save you money in the long run and give you a durable locker that you can depend on.