I also have the Simplicity Rotary Cutting machine and I never use it.
I don't like it at all. It is difficult to keep the fabric straight, the "blade" cuts with pressure and sometimes wouldn't cut all the way through and you can't re-cut a piece to fix that as it would never line up the same. Overall, it is not a very good product.
I do have the Simplicity Bias Tape Maker and I use that with a lot of success to make (or rather, fold and press) binding.