The flying saucer does have a bit of a learning curve, some chins get it quickly, some get it later (sometimes it takes months), some never get it. A normal drum style (chin spin, silver surfer, etc) are easier to figure out how to use. They would be a better chance of them figuring those ones out. I think it might also depend on how your chins react to new stuff, do they ignore it? investigate it? or find new stuff scary? If they investigate things that is the best response and most likely to figure stuff out.