Hi David,
In 2008 I did LT, was close to my ideal weight but didnt refeed properly and didnt do maintenance. Then it was my sister's wedding, my birthday, a holiday to disney world and I kept 'treating' myself all the while. I gained about a stone in 3 months then tried WW for a while and seemed to stay relatively stable with no gains or losses.
In 2009/2010 my job changed, and I spent 3 to 4 nights a week staying in hotels - full english breakfast, 3 course meal, couple of pints in the bar etc... Looking back it's obvious why all the weight came back over 3 years but at the time I felt I deserved the perks for being away from home.
LT is a reliable and rapid way to lose the weight, but you need to make changes for life once the plan ends or it will be a waste of time and money.
Hope that helps
Phil