I'm a little bit disappointed how the product type downloadable works in magento. I'm really wondering why you can buy a downloadable several times (i know you don't have to but it just looks like this with the add to cart button still there).
Is it possible to show the download link instead of the "add to cart" button – if a user is logged in, who already has purchased the product?
And furthermore mark the product as "already bought" in the category view e.g. remove the price?
That would improve the usability and user-friendliness so much and i absolutely don't get why it's not already standard behaviour in magento.