.....well for sure...depends...i could get about 2- 3 aborts per e-tank (typical 5-8 min ea) and around 6+ per m-60. gotta hit the O2 immediately, and i used a 2 oz energy drink on the way...which increases effectiveness immensely. note with the e's you are WAY more portable than a concentrator....had in car and office for 25 yrs...m's at home.
....$ cost can be a consideration if you are renting the concentrator.....will need to do some number crunching as appears you are doing....
...if the concentrator works for you great....not many clusterheads find so. is not 100% O2 and does it take a while to "warm up" to effectiveness? they didn't used to get up to 10 lpm so looks improved, but 15-25 with a tank is easy and effective....
...once i got the breathing technique down, plus energy drinks and D3 i would rarely need the triptans (zomig ns (10 mg) my last resort abort....