It wasn't until I started reading posts on Backyard Chickens that I learned that most serious duck people hope they get ducks WITHOUT crests...and now I understand why.
I have a crested Khaki Campbell x Cayuga duck named Beaker. I picked her out at a farm because she was the only one with a cute crest. My adult drake is a Cayuga named Dr. Bunsen Honeydew (they are named after the Muppets characters). I did both: I artificially hatched 4 eggs and let Beaker hatch 3 eggs during the past 2 months.
I knew that there were some risks for hatching eggs from ducks with crests, but I either didn't realize the extent or didn't want to believe it. It was heart breaking when they wouldn't make it. Out of 10 ducklings that hatched, 7 ducklings survived. The ones that didn't make it after hatching were ones I artificially incubated. While 7 out of 10 isn't horrible, it is possible that the ones that died could have been weak BECAUSE they had the crest gene. I've read horror incidents where the ducklings are very deformed--brains outside the skull, etc.
I've read that 50% are supposed to be crested. Only 1 that survived was crested. I'm very worried about her because she's 1/3 the size of her hatch mates and has a soft spot on her skull similar to a baby's fontanel (but otherwise acts healthy and normal).
I guess my comments don't really help you. I just wanted to share with you my experience. I hope you all the best if you do breed your crested. They are adorable.
A friendly greeting from Beaker (with feather boogers) and Bunsen hanging out in the background:
Curious Beaker looking at the artificially incubated ducklings:
A proud new mama Beaker and her first duckling:
Lifeguard Beaker supervising her ducklings (this was taken a few seconds before she decided to get in that little bowl, too):
Beaker quacking at her babies for wondering too far away from her: