MGB is similar to RNY in that it is restrictive and malabsorptive. The biggest technical differences are that the MGB only requires a single anastomosis and the new stomach is more like a 4-6 oz. sleeve created along the lesser curvature of the stomach. The remnant stomach remains intact, so the surgery is reversible and revisable. Here is a short animated video from my surgeon's website that explains it more precisely: http://mgb-surgery.com/procedure2012.htm There is also a dizzying amount of information on Dr. Rutledge's (the doctor who developed the technique) website at http://www.clos.net/
Recovery time is about a week, but some people say they need another week or two to get their energy back while others say they could have gone back to work in two days. I went back to work exactly one week after surgery and did fine, but I am an child/adolescent mental health therapist, so my job is more taxing on my brain than my body. I think it depends on the job a person is returning to and whether or not they had any complications (I did not and have not had any complications).
I eat and supplement like an RNYer (80-100 g protein; multis, calcium, D, B12, and iron+C throughout the day). The first two weeks post-op are primarily liquids and yogurt, the next two are soft foods, and then it's just a matter of adding foods one at time to make sure they sit well. And, of course, exercise on most days of the week.
Long term I don't know the difference but I had my mini gastric bypass done in 2007 and and over this time period I've never gained one pound of my weight back. If I just stopped eating healthy my weight just stayed the same when I went back to healthy eating and exercise I dropped weight again. I've been at my goal weight for quite some time now and my weight usually fluctuates between 5 pounds during the month account of my female cycle. I know a lot of people that have had other procedures and gained back weight. I was very happy I chose the MGB.