I love easter eggers for heat, I've lived in North Texas and Southern Oklahoma all my life and let me tell you that it's more to do with the body condition in the heat after you've made shade and provided cool water. Any breed if fat enough will die in the heat, I start leaning my hens down around April...fat chickens can't handle 100 weather well.
Always had a feed store mix of breeds growing up and I can't say any seemed better off during a heat wave.
Now that I can choose breeds, I do pick from the heat hardy breeds but always keep them under a close eye for body condition.
I have Americaunas (easter eggers), barred rocks, buff orpington (very fluffy and not good in the heat), black sex link, cuckoo marans (can get chunky) and lots of crosses from these with my speckled Sussex rooster...I kinda like mongrel chickens for variety.
If you give them the right "tools" they will handle the heat well but always keep a watermelon in the fridge, they will love the cold sweet treat!