I have one crested blue swedish from a feed store (Micky) that had some seizures, tiny, weird crest... just a hot mess of a duck.
I was worried because I had already ordered 2 white crested from Metzer's when I first noticed Micky's seizures so I've watched them closely but they're great. The crests look nice and they've never had a seizure or gone spacey or anything.
As far as personality goes, they act pretty much the same as our pekins but none of them are people oriented because there were 14 of them together in the brooder. They do grow slower than the pekins though. Enjoy! and post pics... Are you getting other breeds too?