IMO, I don't like the flymentor cause you are not actually "flying" the heli. It auto corrects and auto stabilizes the helicopter and you never get a true feel for it. When I talk about stability in my videos, and when my heli's can sit in one place for a bit, I have put a lot of time and effort into them to get them setup just right. Once you get a heli setup correctly, it will do what you want it to do.
However, this is your money, and your decision. I don't think it will help much if any because once you take it off, you are going to think that you have an unstable helicopter. But, if this is something that you want to do, give it a shot. Let us know how it all goes if you do.