I am using these page protectors to add to my Project Life album because I seem to have more vertical photos. I haven't put anything in the 12x2 slot yet, but I can tell that the paper is going to slide out. I will probably add a brad or clip of some sort to hold the paper in place. I think I'd be happier with this configuration for the 4x6 and 6x4 photos and just have a short page protector rather that a 12x12.
The pages do fit nicely in this album.