Well, I can see why you have your doubts about colon cleansing and products that claim they can "clean you out". I was also very skeptical, but over the years I have learned different products will help you with different things. I like OxyPowder. Its one of the best colon cleansers, that doesn't require you to mix fiber water & laxative teas.
It is gentle, but you will have liquedy stools while cleansing. This is normal and what you should expect to see, but also one of the biggest complaints about Oxypowder. Most people think it's diarrhea, but that is actually not correct.
Another complaint of Oxypowder is, some people feel that because oxypowder turns everything to liquid, that they are not seeing any "mucoid plaque" or "poop-ropes" come out that it is not effective. But also, because of the oxidation process, everything turns to liquid. The main sign that the oxypowder, or any colon cleansing product, is working, is the strong odor of the feces. If it has a stronger stink than normal, then that is a good inclination that it is cleansing your intestines.
You're already on the right track. You seem to be doing the research into what Oxypowder and other colon cleansing products will do for you. I hope I have answered some of your questions. Good Luck & keep us updated on what you decide.