From what I've read, there is a significant overlap between IBS and obesity, and a reasonably high percentage of patients who get the sleeve or bypass (particularly the sleeve) see positive results. If the bariatric clinic you are interested in is offering any sort of seminar, virtual or in person, I would recommend attending that and asking them about IBS to get an answer from the source.
A recent study from 2017 included both laparoscopic sleeve gastrectomy (LSG) and RYGB patients before and after surgery. One hundred eighty-six patients were assessed using a GI quality of life index (GIQLI). Total GIQLI score and all sub-scores were significantly improved within 24 months after surgery, and these findings were more robust for those patients who underwent LSG. Possible sex influence on symptoms was analyzed and no difference was found in total GIQLI between male and female patients. These studies consistently show that bariatric surgery is effective in reversing functional GI symptoms.
That being said, most studies I've seen state that more research is necessary to definitively state that bariatric surgery will reverse IBS, but it certainly looks promising. It's definitely a question you should ask a bariatric medical provider and/or surgeon.
