It's interesting we were having this discussion. I was looking for Austrian standards for alsteirers for Pens. I read something that said they all should lay at least 55 gram eggs.
It reiterated over and over to pay special attention to that and any birds laying smaller than 55 gram eggs shouldn't be used for breeding.
It said whether breeding for hobby or exhibition, please do not use eggs under 55 gr for breeding !!!
Apparently it is well known the effect hatching from small eggs has on future generations.