My female BRB gave me a nice litter last year. The babies all came out nippy but settled down quickly with regular and consistent handling. The last time most of them nipped was when prospective buyers were popping them for sex, most took great exception to being "violated" in that manner. Even when they do nip it's not a bad bite, usually it's much less painful than what you would get from a playful kitten. I've never had an adult act defensively nippy.

I also have an MBK. She was a doll her first year, very easy-going and chill, never offered to nip at all, sweet to handle, etc. She goes off food a bit over the winter along with my other colubrids - they don't stop eating entirely but they only take a feeder every 2-3 weeks instead of weekly. The downside is that once spring hits she gets voracious, and she will go for fingers thinking that they are "pinkies" even if there is no feeder smell in the air or on my hands, so handling her can be a challenge in the spring now that she's an adult. If she's not foody she's also good to handle.