I do not find Pilates relaxing or helpful for IBS symptoms. I have been addicted to it for about six years now, but have only been diagnosed with IBS a few months ago.
Yoga is probably much more relaxing and helpful for people with IBS. I usually do Yoga in the winter months, but have not done it at all this past winter b/c the last class I went to I had really bad GERD at the time and one more downward dog would have made me ill!!!
I'll go back next winter since I'm feeling much better these days