You're right Uniquity, and like I said I would really like to hear Andreas' answer on this as well.
The only thing I can offer from my own research on Dr. Christopher's LBB is that is it taken for a period of up to 9 months and doesn't contain a fibre element, as opposed to a similar (albeit 2 week) programme by Dr. Schulze's, which contains a fibre product plus a herbal detoxifier.
From what I can gather, perhaps the herbal formula contains herbs that may not benefit one's body type, or may be irritating (such as cayenne for pitta types). Also, a 9-month programme is more like a gradual maintenance type cleanser which could also be achieved through correct diet (as you have also acknowledged), while oxypowder and the rest act quicker using the subject of peristalsis to be dealt with by lifestyle changes.
Since I've already done a large series of bowel cleanses via enemas (which also don't do much for peristalsis) and twinking with my diet I've seen my colon improve, so I wouldn't say no to 20 days of additional cleansing with epsom salts or oxypowder. I wouldn't say no to the herbs, either, but they're quite expensive, plus I don't know if they'd be the right thing for my body type.
Anyway, I'm probably just repeating myself here and throwing in a few wild guesses too. So, lets wait and see what Andreas has to say!