I have never used a zafu before. I am 5'9 and about 220lbs. Not the most flexible, but willing to cahange that. I had been using a stack of regular pillows for sitting, but they are very unstable and have led to some back pain. I was wondering if anyone has any information on size, filling contents, and if a zabuton is worth purchasing. Where do people generally buy these? Are there good dealers who you've done buisness with before?