* I can earnestly say Kerrygold (or Irish butter from ALDI) makes a real difference than regular butter.
* I can say that kosher salt does help as well.
* I found a difference with (fresh cracked) white pepper but I don't personally prefer it over black pepper.
But most surprising to me (and what confirms your thesis) is I did not find a difference with the freshest of local eggs. I purposely went directly to a local farm with their own chickens, but nope- still the same as mass market eggs.