Not leaving the remnant stomach is an option (that is what is done when the surgery is for something like gastric cancer - you don't want it lying around in there, lol) but there are trade offs as usual. The main one that I can think of is that the stomach is no longer there producing acid to neutralize the bile being secreted just downstream of it, so there may be greater chances of bile reflux. AFAIK, there are ways to minimize that when the surgery is done, but these are things to discuss with the surgeon as to how best handle your individual problems. If I had revised my VSG ro an RNY a few years ago, that is how it would have been done - no remnant stomach.