We are looking for a way to take partial payments, actual partial payments like deposits. There do not appear to be any apps that enable this correctly.
Using variants is not working for us as shopify creates a new SKU in DEAR Inventory which obviously has seperate stock levels. All we need is for these variants to be pulling from the levels of stock for the pre-order products whether they choose to use the 10% deposit variant or the pay in full variant.
Here is a link to one of the products with these variants, the product is identical it is simply a different initial price point.
We have updated Our App "Advanced Preorder" where user can pay deposit amount along with lots of features. Please have a look on it and you will definitely find it same as you are looking for.