Not sure about other folks' Crevies, but my mom has very small horns that you can barely see at the base of her crest. Her egg production is seasonal and she lays a very nice quality petite white egg. It's really similar in size to a LF Polish egg. When she's in season she'll lay daily, but out of season she will sometimes not lay at all. I honestly wouldn't recommend them for egg production due to the size and frequency issues. (In our household we live by the motto "every egg is precious" so as many as possible are being hatched, not eaten.)
That said, we really need as many people as possible interested in the breed if it is to survive, and they're honestly the most intelligent chickens I've ever raised (and I've been breeding show poultry for a very long time.) I know my sample size is small right now (only mom and dad are adult) but all of their babies are coming out with the same personality and joie de vivre. If you're considering a Crevecoeur, I say go for it! They're a blast!
I love that owners share about the good temperament of their Crevies. I came close to looking for a breeder to add a gentle hen to my gentles flock but one owner said her Crevies refused to go into their coop to roost and kept flying up into the trees to roost. It was the one negative that kept me from actually considering the Crevie. Small or less eggs isn't an issue for me but having a breed that stays in the yard is critical in my small yard suburban neighborhood. Crevies, Polish, Silkies, Cochin bantams, Sultans, Breda, Ameraucana, Araucana, and occasionally some EEs, fall under the gentles 5-lb-and under category. We stay away from LF, heavy, or dual-purpose breeds to eliminate dominating bullies in our smallish backyard. We love bantams but have to stay away from the flying varieties. Hence we have the flightless Silkies and a gentle BW Amer. We're expecting another Amer (blue) and Blue Breda juvies tomorrow morning thru USPS. I am crossing fingers these two new girls will be gentle smallish additions to our current 3 hens.