Breadcrumbs or flour when greasing and dusting a cake form?
i only have one recipe that calls for breadcrumbs, which is my hungarian torte (uses almond meal) and I use fine purchased breadcrumbs. I've never really noticed them but the cake does come out nicely. There's no issue from a flavour perspective as they're often used in sweet foods (like strudel) to absorb the moisture in the fillings.
I would use flour unless the recipe called for breadcrumbs, but you only need a very light coating...shake around then tip out and tap well.