We have added a requested feature for variants with infinite qty. This is for items that the client intends to drop ship and thus does not have to worry about their qty on hand. The rule of thumb is that whenever you are making a template conditionally show a product/variant as being available for purchase, you should use in_stock? which is now available on the product and variant drops. There is also an infinite_qty? attribute now as well on the variant drop and a has_variants_with_infinite_qty? attribute on the product.
The default templates have been updated to make use of these attributes so be sure to check them out.
Here are some guidelines: