Without specific examples I can't really comment but part of the difference between phase 2 and 3 is not the "number" of carbs, it is the type of carbs. That is why the best thing is to focus on the food lists, not the carbs or calories in the nutrition facts, because all carbs are not created equal.
I think the Mayo Diet is a good one if you are talking about the Mayo Clinic Healthy Weight for EveryBody book, not the fake one on the internet with the eggs or grapefruit/etc.
If you decide to combine diets, I would count calories too, using fitday or something similar. Watched part of the half ton man last night on TLC and the doctor said he had one guy who was morbidly obese who ate lots of oranges, and couldn't figure out why he was fat because all he was eating was oranges. The doctor told him one orange is healthy but 45 are not.
I think the bottom line is on all diets you have to reduce your calories to lose weight. To lose a pound a week, you must eat 3500 less calories than you are expending (or 500 a day). You can figure out what you are expending each day by using the basal metabolic calculators on the internet and then calculating your target calories based on that.
If you count calories on your own plan, you will undoubtedly be successful.