I used these for my 54' and 55' Topps sets. I am in the process of rebuilding and had just brought this empty one back out. I didn't have any issues that were mentioned above, I love them. They are a little sloppy if you have all your sheets in, and only half the set just due to thickness because as you pointed out, they stay in a plastic holder set into slotted pages...but I'll say these work really well for me.
I will add that they won't hold a set as big as 56 Topps, just too many cards. Sorry I couldn't get the pictures the way I took them, they are sideways...lol.