Yup I have ulcerative colitis and one doctor put me on FODMAP, my awful symptoms were minimized much the same was as taking almost chemo-level pharmaceuticals I was put on at an earlier time (which also was effective). That time around I wanted to try a diet approach and it seemed to work. And traditionally there have been no diet based remedies for colitis, whereas with Crohn's and celiac diet matters a lot so that says something for FODMAP ancedotally.
The only problem is the it is really hard to find FODMAP food in grocery stores. You end up eating a very small group of the same meals and are forced to not eat out at many restaurants. So much like weight-loss/working out you'll be receding back to eating regular food within a few months unless you're dedicated.
I hope the 'food industry' starts offering more food in the FODMAP genre, instead of the obsessive and over-priced gluten-free products that are popping up - and largely not science based the way FODMAP has been.