Edited to add: LOL I just realized this thread was way old... I wonder how it turned out? Oh well, maybe my response will help someone else.
I think all of these programs are really intended for longer term use with gradual transition to whole foods, BUT if you are really set on using one just in the short term, I'd throw my hat in with Medifast.
But if you do it - you should be 100% on program for that month, or else you're just wasting your money, and it is pricey. It's completely worth it to me because it got me out of basically a 5 year funk where I felt like diets and exercise just weren't working.
I think if you carefully control your calories and carbs immediately after going off of MF, you won't experience that immediate re-gain that people have if they go from doing Atkins to eating pasta and cheese fries the next day like I did 5 years ago.
Also, Medifast is not an extremely low carb program, just low enough to keep you from being hungry all the time. Just one of the bars can have almost as much carbs as I would eat in one day on induction of Atkins.
I like Lisa's
idea of prepping her own small meals - I think that's what transition and maintenance is going to look like for me after hitting goal. Because every time I buy MF food I think, WOW that's a lot of money for 7 smores crunch bars.