Maybe I missed something. You seem to have only made pre-minting more efficient, but that isn't a sale. So you the actual sale is a transfer which costs the same amount as a mint would have otherwise. Why pre-mint anything at all since it's not being used until it's sold? It seems like the most important step in this process which is the sale is still the same. In fact ERC721a makes that step more efficient for your customers who bulk mint. Why not combine them?

So with what you have here your minters will actually spend more than ERC721a on bulk mints. Isn't it a more typical use case that the first transfer is to the customer and not to yourself? If you bulk mint to yourself and then do 100 single transfers to a customer what has been saved?