No matter what diet you do if you go back to the bad eating habits you had before then you will gain weight regardless of if you do SW or VLCD. There are many on here myself included who have done SW and it didnt work for them you have to find something that works for you. There are people doing SW who've done VLCD put the weight back on because they ate terribly again. In my personal experience I actually picked up bad eating habits when on SW before I started it I was eating salads and veg and losing weight I joined to support someone I know and just ate nonstop as when ever I didnt have a loss people would say you're probably not eating enough. The whole free foods and superfree thing with syns mucked up my views because actually our bodies burn calories not syns if I have over 2000kcal with all my free superfree food and my 15 syns I will not lose weight. Your body loses weight by calorie deficit.
For me sns has made me wake up again I use to eat so healthy but I got lazy not wanting to cook to separate meals eating potato which I dont really like. If I dont want something fatty when I'm out with friends I can say no and have something healthy without feeling like everyone is thinking I'm boring. This diet has completely reignited my passion for healthy cooking. I've realised its ok for me to be hungry its not life or death I dont need 2 sandwiches to fill the void but I also dont need as much food as my nearly 6ft boyfriend who was I trying to kid?
Its all about the persons commitment to a healthier lifestyle for the rest of there lives for me I've gone back to how I use to eat before I started to gain weight loads of veg and lean protein. My gain all started when I moved up here my weight dropped from stress to unhealthy levels for me and then I started to eat more when I was dating my boyfriend because I was afraid he'd think I was dull at first which is ridiculous he's perfectly happy if I don't want to drink or share a bar of chocolate.
When you go away on holiday both sns and SW would advise similar foods that being lean protein and veg only difference that SW would also allow pasta neither are gonna say eat as much ice cream as you like and when you go on holiday you will probably put on a bit of weight on both diets as you have no real say at a buffet (guessing as you said AI) how foods are cooked.
No one can say what is the best diet for you because we are all different its about what you do with the rest of your life not the few months you spend on whatever diet you have to commit to being active throughout the day not just 30 minutes walk in the gym but doing things that keep you active but most importantly you enjoy doing