Well, this is a very timely topic, as we are going back on the South Beach diet, starting tomorrow. We did it 4.5 years ago, during my last term of nursing school. It worked very well for us - I lost 10 pounds and Todd lost 26 pounds, in 6 weeks, but then he got laid off, I had to go back to work full time for the last month and a half of school, and it all went to hell.
I am very frustrated, because I have not lost a single pound, since I started running, last September. I went from no exercise, to running/working out 1 hour/day, 4-5 days/week, without changing my diet at all, and I haven't lost any weight. I don't know how that is possible. And it's not because I'm building muscle, because my flab layer is unchanged. I'm blaming sluggish middle-aged metabolism.
So, this time, I want to lose 10 pounds, again, and Todd wants to lose 32 pounds (I posted 40, in the running thread, but he corrected me.
Elissa - you are completely right about different methods working for different people. And, as I am unfortunately learning, what works at one stage of life does not necessarily work, as you get older.