N.G.
I have lap-band. I had my surgery in September of 2010. I've lost 96 pounds. My highest weight was 375.
I'm glad I got my band because I feel better than I have in a LONG time. However, when I'm not willing to do the work, the band doesn't work. Period. It doesn't do the work on it's own. I'd say that losing weight with the band is about 90% your effort, and 10% the band. A lot of people wonder why they got it in the first place, since you still have to diet & exercise diligently to lose the weight. For me, it gave me a sense of hope that I wouldn't otherwise have had, so I was able to lose the weight.
My insurance didn't cover it so I paid cash. The fills are $200/pop. I don't know if medicare covers it or not, though I doubt it.
Medically I haven't had problems with it. I do spit up food now & then when I find myself eating too fast. You have to take very small bites and chew a lot, and there are some foods that I just can't eat any more at all.
Do you know for a fact that your MIL isn't willing to change? If she's not, then lap-band truly isn't for her. It won't do her any good.