The problem I see with pellets is that you have no control over what the price does. No matter what you get I'd plan for storage even if you add it later. It really don't cost that much in the whole picture. Many of the boilers out there can be run without storage, but I don't recomend it. Look at page 4 of fine tunning the biomass sticky for what the tubes look like with and without storage. That should be enough to convience you right there.