BTW, I believe eggs/crates are in the same loot table as chests and they are simply the "legendary" rarity items from that loot table:

White/Common = Copper Chest
Green/Rare = Silver Chest
Purple/Epic = Gold Chest
Pink/Legendary = Locked Grand Crate of the Watch/Egg

So there are occasions when a luck elixir may actually bump you from an Elite Golden Chest to a Locked Grand Crate of the Watch, which if course most would consider a downgrade. But it can happen.