The ability to use available Blizzard Balance toward a purchase as a partial payment along with another payment method would be a very helpful functionality addition to the checkout process.
Ex: Amazon allows users to apply their Amazon Gift Card balance toward a purchase and pay the rest of the amount with another payment method.
If the Blizzard Shop can adopt the same functionality, this would allow consumers to better utilize their Blizzard Balance and address the pain point of having unused Blizzard Balance sitting in our accounts (Or else, to go through the process of adding to the Balance and waiting for it to apply before coming back at a later time to make the purchase, and then possibly having more Blizzard Balance left over… You get the idea. It’s an annoying cycle of seeing unusable credit sitting in our accounts.).