(read details please) Can The Ikea Lack Floating Shelves Be Used As Bookshelves?

I have a ton of books, and I want to change my room, so I'm thinking of getting floating shelves and using them instead of the bookshelves I have now. I will probably get these: http://www.ikea.com/us/en/catalog/products/60103750 or these: http://www.ikea.com/us/en/catalog/products/60103632 . Do you think the weight would be too much? I would probably fill the entire length of the shelves. Thanks!