This year was the first year I ever tried O2, and did abort the headaches. Problem is that I would go through a tank per week and, when things were particularly rough, an entire large tank in one night. Getting a new tank delivered for the next night, especially on short notice, was not always easy. I figured that if I had a concentrator I could just use it without worrying about running out and spending hours the next day arranging for refills/pickups/dropoffs/etc. I think you're right though - getting a couple large tanks at a time is probably the way to go.