Going from GVB to Bypass
GVB? Can I assume you mean the VBG, Vertical Banded Gastroplasty? How certain is your surgeon that he can do this revisions? The old VBG often caused so much scar tissue that revising to a Sleeve or a pouch isn't possible.
I do know one lady who had a VBG that revised to a hybrid DS. They would up just leaving her stomach alone, but gave her a DS intestinal bypass. She's at goal and maintaining pretty effortlessly, even though she really has no restriction.