The hens for the lavender & mille are VERY sweet. One lav hen is a little nippy, but that's more a search for treats and not meanness. She's lowest on the pecking order.
My butterscotch d'Uccle hen is very flighty and not the usual temperment. I got her from somewhere else and am hoping her babes are more settled.
Most d'Uccle roos are sweet when young, but get a little persnickety when they get mature and start to worry about their flock. My Mille roo has been beaten up twice by a dog while protecting his girls, and is AWESOME at watching for hawks and other dangers. He has bitten me a few times, but only when I'm close to the hens. I tolerate it from him because I know he's got a high defense instinct. When I pick him up he's as sweet as can be, and very patient.
That said, I have no tolerance for meanness in young cockerals. If hugging doesn't calm them down then they go to freezer camp early (and feed raptors at the rescue center later on). d'Uccles are meant to be sweet birds!