At the hospital where I trained, there was one surgeon who performed many bariatric surgery cases. I will try to keep this anonymous.
He only used the gastric bypass (gastric exclusion plus small diameter gastrojejunostomy) procedure. He felt that the other procedures did not work as well, particularly in the long term. He was particularly critical of the vertical banded gastroplasty, because he said the "tube" created that connects the proximal and distal gastric pouches enlarged rapidly, preventing long term effectiveness. As he put it, as soon as one of his patients leaves the hospital, McDonalds "calls out to them, eat here, eat here!", i.e. they STRESS their suture lines.
Most of his patients lost over 100 lbs in the first year and then leveled off. There was a fair share of perioperative complications, including some anastomotic leaks that caused varying degrees of catastrophes.
However, having done many of those procedures and participated in the patients' followup care, I can honestly say that the most important part of the surgery was the ancillary support staff. He had full time nurses and dieticians who rigorously followed each and every patient. They were extensively evaluated preoperatively, which always included a psychiatric evaluation to make sure they could handle the psychologic stress of no longer being fat. Many of the women (or so I was told) ended up getting divorced after the procedure, because their husbands could not deal with having a wife who was NOT obese.
If you become involved in such a center, make sure you evaluate each patient carefully and recruit a motivated support staff. The surgery alone may work for a while, but it will be lifelong dietary modification and psychological support that will ultimately contribute to the success or failure of your endeavor.