I have 20 Cornish X from Mt. Healthy here in Ohio (on special at TSC, couldn't pass them by for only a buck each) that are five weeks, old, and some peeps from Meyer that are just five days old. So far, there is a big difference. I'm surprised by how bright yellow the Meyer peeps are, and by how calm they are. Don't think I've ever seen such calm chicks. I wonder if anyone else has experience with Cornish X from different hatcheries. I'm very interested to find out whether they dress out at different weights once processed.
Mine have always been super calm like yours from Meyers. Maybe the calms ones will influence the others. Good luck.