I think Montmorillonite is the same or practically the same as bentonite.
Many people have a lot of success mixing the clay with psillium to make a shake, commonly referred to as P&B Shakes.
I use Bentonite clay on and off. It works well. I'm partial to DE and use it daily. I've mixed the DE with the Bentonite clay and pretty good results with that also.
You should definitely try the P&B shakes for maximum benefits.