LAP BAND TO GASTRIC BYPASS DISTAL
I strongly urge to you consider the DS (duodenal switch) as a better option. While the DS gives more malabsorption of calories, it actually allows BETTER absorption of many vitamins and nutrients, because it keeps a fully-functional (although smaller) stomach and a small portion of the duodenum---and it has the very best stats for weight lost and kept off over time.
I'd consider a Vertical Sleeve Gastrectomy instead. Similar results (84% of EWL)... but no malabsorption. It's basically the first part of a duodenal switch (90% of stomach removed, although pylorus in tact) without the rerouting of the intestines. 80% of people who have it never need the malabsorptive part... but that is an option should you ever need it. Go to the VSG Forum for more info. Most lose 50-70 lbs in the first six months. No lifelong nutritional issues.
Why didn't the Lap-Band work for you?? Fills a pain? Too much PBing? Didn't lose as much as you'd thought??? Explore that before you go after another surgery. Why not a regular proximal RNY over a distal one? Seems like your surgeon is rather aggressive... not necessarily a good quality in a surgeon.