I have this and I use the large size for 2.5" binding strips. It works fine for me.
I always wait and let the machine get good and hot. That means I wait a few more minutes after the light comes on to tell me it is ready.
If I ever feel like it is not creased well enough, it is very easy to run it through a second time, but I don't usually have a problem.
I use this for all of my binding now. It beats pressing it in half!