I don't have any personal experience with them. For such a long time I've read articles and heard how they aren't effective. However, I read an article a couple weeks ago about how they are starting revisit the idea that they may be productive.
If you can afford to buy it I certainly don't see anything wrong with giving it a try. As long as you stick to your plan of adding this to your current exercise it should be OK. Just don't fall into a habit and let it replace your exercise.
Let us know how it goes if you end up using it.