As you've heard Lighter Life is £66 / wk but you eat nothing other than what they give you. No food, no drinks (except water, black tea, black coffee), so although it is expensive if you add up in a week what you spend on food (including coffees, snacks, chocolate, fizzy drinks, meals, take-aways, alcohol etc) it's actually not so bad. Plus it includes a (compulsory) hour of group counselling every week (to which I initally thought - NO WAY AM I DOING THAT - but which turned out to be absolutely brilliant for identifying why I had let myself become overweight in the first place, talking about childhood influences on food, parents, etc etc) Anyway it changed my whole attitude to food (ie - eating is not about recreation, comforting yourself, dealing with boredom, fitting in, politeness in social situations etc etc etc food is fuel for your body - think about it!)
W8 is a very similar concept, cheaper (about £46 I think?), and the soups, shakes etc apparently taste much nicer than the Lighter Life ones. It is also more flexible - there are a choice of programmes, some with food included in them. There is no counselling as such but you still get a weekly weigh in and group session with lots of support. Apparently (my friend is a W8 franchise holder) her results are just as good as Lighterlife even though food can be eaten (in certain weeks and in controlled quantities).
In answer to the question about keeping the weight off it just depends on the individual I think. I finished the programme at the start of May - was 9 stone 4. Then lost another 3lb whilst re-introducing food, and my weight settled between 9st 2 and 9 st 5. Haven't found it difficult at all to keep it off as my attitude to food as a 'reward' has been changed so I don't use it in that way anymore. I'm also not keen on crisps anymore (which used to be my downfall and have also 'gone off' chocolate) which helps! I'm currently 3 months pregnant now and have put on a few pounds but that is purely from eating loads and loads of carbs (which I wouldn't normally do) to combat morning sickness. I am confident that if I need to lose weight after the baby is born/weaned I'll just go straight back on the plan again - although would probably use W8 this time.
Hope this answers your questions - sorry it's so long winded
Good luck in your weight loss quest to all of you. Keep at it! Any more questions I'd be happy to answer them.
Oh and by the way my DH moaned about the cost and kept telling me I'd never stick to it - to start with. After 4 weeks I'd lost well over a stone, was much happier, healthier etc - guess what, he stopped moaning and encouraged me like mad!