Really wish I would have found this guide about 2 months ago when I first dove into pressurized CO2 and ditched the 2 litre. I would have never bought the Red Sea paintball tank kit. I had convinced myself how much better it was due to size and that it would fit better in my setup, but after running to the paintball store every 2-2.5 weeks to refill the 20oz canister, I realize not only was the initial cost of the system ($200 + $40 for the tank) high, but the continued cost is worse.
Another one of those times I was impatient to get a project going and let the LFS talk me into something. Though I did discover that the paintball system regulator will work with 2.5lb+ cylinders, but it isn't the overall best quality regulator.