I think I have to agree. The idea of something going in, makes me a little nervous.
Although, I'm also not sure that doing a cleansing product at home is the best idea either. While I have used Oxypowder, I think the best method is to eat a proper diet and have an active exercise routine. This will help with the problem from the beginning, and hopefully prevent future problems.
But if you're like the average person who eats alot of junk, then I would recommend a colon cleansing product over the hydrotherapy.