I LOVE the TH on the edge dies and have quite a few...I want to get that envelope as well.
I'm sure you will really enjoy them!
I use them on the edge of photo mats or BG papers as well.....no need to limit them to mini books!
The file tabs one you can actually use on any size (only limited by your machine) cause you can easily cut off the excess after it cuts the tabs. It's one of my favs!