HI! When i did the pre op diet and lost weight, I thought the same as you, why should I have the sleeve. My husband and I discussed it and he said, but without the sleeve you won't maintain this diet. He was correct, as I have been a serial dieter for years, losing weight and regaining plus. I am now 61/2 months out and I am almost at goal. I eat healthily and what ever takes my fancy, but I eat much smaller portions and do allot of exercise. I had portion control problems and as i never felt hunger or fullness, it meant I could always have huge portions of healthy food. Since the sleeve, I now having the hunger and fullness feeling and so I know when to eat. I have also avoided anything that might set me off on a binge like crisps which were my biggest downfall. Good luck with your diet and the sleeve.

You probably could loose all your excess weight with the pre op diet, but you would have to stick to it for the rest of your life, in order not to regain...
Without kidding, I think it is very common for people to think this way when they do their pre op diet.
I have been sleeved for almost two years now.
To answer your questions:
My restriction is excellent, I can only eat about 6 or 7 oz, depending on the density of the food I am eating.
I can eat anything I want, but I choose to eat almost 100% healthy choices and sometimes I eat something like pizza or cake or whatever.
A typical day for me is:
B: yoghurt with homemade granola with nuts and seeds
S: fruit, mostly banana and a coffee protein shake
L: whole wheat crackers or bread with cheese, or a salad with some sort of protein
S: homemade carrot muffin or oatmeal cookie (no sugars and extra protein powder)) or cottage cheese
D: protein and veggies
S: handful of nuts

Because I don't eat meat I have to watch my protein intake, so I supplement with the shake.
I know for sure I could not maintain my weight without my sleeve!

Thank you, this was very useful.