[pro4nut]

The AE are made of high carbon steel of a good quality, somewhat better than the zx5 ones.

Ceramic is a winner though as it is harder and they are 'more round' (really!!) So they last longer and the diff action is smoother. The diffs in my pred are of the ceramic ball type and have never been rebuilt since i got it (it was one of the first 50 or so that were sent out) I am sure that Jim would confirm how smooth they are.
You would be better served paying out for ceramics once rather than metal once or twice a season.

Also check the prices for the hpi ceramic diff balls for the pro4, they will work as well