I still maintain my position that dairy yogurt has nasty effects on IBS. Milk proteins and lactose cause problems in IBS'ers. I do not recommend using yogurt from an animal for it's probiotic claims. Bottled probiotics are much more effective and less problematic. I doubt that Heather would advise ingesting Activa yogurt. Yogurt may not give you gas, but it could interfere with your stability, i.e. causing cramps, D or C attacks, or bloating.
If you're craving yogurt, try a soy-based variety.