This is why I get aluminum tank... lighter too.
Depends on how you going to fill the CO2 when it empties, you may not want to do that. For example, if you are swapping a different tank, then you will need to do it every time you get the CO2 refill. However, if you are getting the same tank back, then it maybe worthwhile, at least for about 5 yrs or so. These tanks needs to be hydro-tested every few years, and you may not get the same tank back.