And I can't stress enough that they should not use Shopify. They said "total control" and independent. That is the opposite of what Shopify provides. It sounds like you love Shopify, that's great for you. Some of us like to actually develop websites and customise the checkout proecess, the cart, the categories, the product pages, the collections, the wishlists, the account membership, the invoices, reports, .... the whole lot. It's good to have control rather than be tied to some fast food e-commerce solution.