I used to have very severe IBS and now it's much better ~ I can eat hard cheeses like old cheddar and mozzarella; plus yogurt (Source) and yogurt ice cream without any problems, but I do measure the servings (ie about 1-2 oz cheese and 1/3-1/2 cup of yogurt or yogurt ice cream).
I can have Parmesan or Romano Cheese on things like Pizza too with no problem (1-2 tbl). I can eat cheese slices and processed cheese too, but I usually have only a small amount at a time (ie one slice or a tbl) ...
For my cereal I can use homemade skim milk made with the powdered skim milk (it tastes best after being chilled) without any of the IBS symptoms, but I do still get the conjestion issue from it for an hour or so, but that isn't too bad, so I can live with that a couple times a week (the rest of the time, I have eggs/toast or something else for breakfast).
However, I cannot eat regular ice cream (esp chocolate for some reason) or I get the runs and pain and gas within 1-2 hours of eating it; and I learned that again last Saturday night.
I haven't tried the pills, but my MIL has and finds they help her ...