The Dimitrovgrad market is mainly on Sunday. I have been there. Need the whole day to walk through... Have you been there or want to go?
The green shelled CZ dominant - I have these and they are laying ok. I bought eggs from the exclusive importer in Bulgaria and hatched them on a broody. I bought eggs from 5 CZ Dominant breeds : Exchequer, Black Leghorn, the green shelled, the dark brown shelled and Sussex. I hatched them all on broody hens. Black Leghorns - all died around 2-3 months of age. Sussex- didn't hatched well, but what hatched is OK. Exchequer - didn't hatched well and subsequently 1/2 died. Anyway, overall I am not impressed by healthiness of the chick's. Looks like hybrids are not so strong and no immune system at all.
I might travel to bulgaria in april, not sure yet. do they sell poultry in the dimitrovgrad market?
as for cz dominant I agree they have health issues. I guess inbreeding is the cause.