Does the Proform Ab Glider work? What about the Ab Circle?I'm kind of interested in these machenis. Do they actually work? I feel like I can't trust the commercials or even some of the public reviews. Maybe I'll get better answers here!Thanks for any advice about it.Please don't give me any purist arguments about not using machenis or what not. If you have advice on these machenis, then I would love to hear it. Thank you.