Re: carbon fiber or normal tank
Those non-wrapped tanks are steel. The 72/3k you linked is way heavier than most CF tanks. The CF tanks are lighter and highly reccommended. I'd pick the 68/45 from your links because it has a 5yr hydro schedule. Means you can use it 2yrs longer before having to take it in for a hydro than the 72/3k and 68/3k.