If I am right all these parts are reviewed but as you will understand when I have new parts I first have to drive with them.There after it is possible to tell something about the performance or it's durability.If I am not mistaking you still get info about the Spiral gear and the light weight spur.
I can tell that they both perform well and there is no excessive wear I have driven the spiral gear in the rear almost whole last year and it looked still good so I decided it would hold for an other year as rear diff.For the front their is no need to replace as I sometimes drive torsen (standard gear) and I use more normal diffs with spiral gear but with different oil for quick replacement so the wear of front diffs doesn't go that fast as I use more then one.The light weight spur is as good as the standard one so also in this case no excessive wear.
For this year I have replaced the parts as I already mentioned in last year review