G'day Luke,

It's a great question.  For context, we have sold nearly 600 of these egg carriers.  The 12 egg / dozen eggs carrier is exactly the same, just has double the egg spaces, and we have some 5-star reviews there.
It definitely only takes small eggs, so if you're used to buying 700g/800g dozen, you'll have to go smaller.
The only real-life experience I can offer is from my folks who use one from home-laid chickens.  Cant confirm their egg size though sorry!

I'd love to check for you, but we don't have any eggs on hand!
Best I can do is confirm the egg sections are 4cm wide by about 6.5cm tall.

Hope that helps.