http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3410227/

"Band malfunction (insufficient stomach restriction) after AGB leads to weight regain (73–75). In contrast, gastric dilation after VSG does not necessarily abrogate weight loss. Gastric dilatation is not common after VSG, estimated to occur in only one of 14 patients 1 yr after surgery (66), but when it does occur, it is unlikely to limit surgical success (66, 72). Furthermore, gastric tube size does not predict excess weight loss in humans (76)."

Almost every single study out say that the tube sizes doesn't matter in forming the sleeve in the weight loss, but people and Dr's still insist on the smaller ones or act like it makes a difference when science and common sense, says it doesn't

When you look at the size difference it is so minimal it is comical.