I can answer some of your questions about The Simple Diet (which I'll refer to as TSD for short). The exercise is stressed as important, but you don't have to do any more than you can handle. The 2000 calorie target is just that, a target, something you work towards as you are able.
I don't get anywhere near the target. One of my reasons for switching to TSD was that I was experiencing such pain and fatigue from my fibro, arthritis, and AI issues that I didn't have the energy even to prepare meals.
As to the speed of TSD, it is comparable to any other meal replacement plan. The factors that affect speed the most (in my experience) are calorie intake, carb intake (for those who are carb sensitive) freggie intake, exercise, and to some degree water intake (there's no need to drink more than 3 quarts of liquids, but fluids will help prevent constipation which can can cause gains and reduce losses on the scale, at least until resolved).
The book isn't necessary to get started, but I would highly recommend reading it at least once. I borrowed mine from the library, and initially had no plans to buy it (though I had taken a few notes).
I ended up buying the book on kindle (which I now have loaded on my Nook), because the book has many tips for maximizing weight loss.
The Dr. Anderson's Simple Diet thread here has all the guidelines for the shakes, bars, entrees, and soups.
The basic formula is 3 shakes, 2 entrees, and 5+ sevings of veggies (no fat or sugar added).
The author says that people who eat the most freggies are more successful, and I've found that true for me, especially if I choose the lowest calorie options (you can have sweet fruits, avocado and starchy vegetables such as potato, legumes, and corn, but to maximize losses you would want to pick the higher water and lower calorie freggies like greens and berries).
I've been on a lot of meal replacement diets over the years, and I would rate it as the absolute best, because it gets high marks in all of the factors important to me - cost, results, simplicity, ease of following and ease of food preparation, variety, nutrition, hunger-control and food taste.
There are a few diets that might score as high or higher in some of those categories, but none that can come close to competing as well in all of them.