Typically if any differential is needed, slightly more down than up is desirable for aerobatics.
Odd thing about the Kaos is the forward slanted horn on the bottom side of the elevator gives more up than down. A bit counter intuitive but still, its a proven formula on that model so I wouldnt change it.

Again, with computer radios its a bit of a moot point anyway, you can dial whatever differential you want in about 2 seconds. Gotta love technology!