For the use being discussed (teaching beginners), you really need 9 stones, and it needs to work well. 7 stones is getting close though. I'll take a look at those games.
Last I saw I remember katago playing up to maybe 4 stones pretty well but the games being poorer quality over that.
You wouldn't know that from watching JBXKataBot playing on KGS with a typical 5-7 stone handicap.