Make Product Type an option in Product Reference

Dear Commerce team,

I'm building an eCommerce site for a publisher, and I've got product types Paperback, eBook, and Audiobook all linked by Product Reference to the Book node.

The Product Reference select list has the option to display either the product title or the SKU, but not the product type: instead of letting users select "Book Title (ebook format)" or having to pick books out by their ISBN, I'd like to make a select list that just displays formats, ie, a list of the product type categories that book appears in.

Having a look through the module it seems like it shouldn't take much extra code to make that an option: adding another setting in the field_formatter_info() hook and using a different bit of information from the product in field_formatter_view. Should I make a patch to do this and post it, or take a step back and figure out how to override it from the theming layer?