Well, if you aren't racing, I'd ask the following:
Why do you want to change?
Is there something that's not working the way you want it to?
Is something broken so you're considering upgrading instead of just replacing?
I wouldn't go with the one-way if you're just running the car for fun. You'll lose front brakes.
Ball diffs are a performance upgrade that allows you to put the power to the ground better. If I were building a car to run around on the street with, I'd probably just stick with the stock diffs.
2010 Big Fat Turkey Race Mini Cooper AAA Main Champion
*** currently in stasis ***