I've not had any problems with heartburn from using a Kuerig for around 5 years.On the rare occasion that I have coffee at my office, I typically get heartburn. It's a Kuerig with re-usable filter. I don't have the issue at home, so I always associated it with a difference in coffee quality. I had been told that the oils were good, not bad. I'll have look into this some more. Thanks for the tip.
A friend, OTOH, had to throw his out a few months ago because he had some serious problems. He researched how he was feeling in regards to a Kuerig. He found a few links associating stomach problems to Kuerigs. He tried to clean his one really good time (already regularly cleaned it, and he found white particles floating in the water. Quickly chunked it at that point.