Both? I mean, I really like the way FZ barrels look, and at the same time, I want upgradeability beyond just a double barrel. I do on occasion find I'm storing more than two barrels, but less than a DSU worth of things. Sand for example. Comparator abilities are handy, as is the ability to have redstone emit on a full barrel. Being able to tell AE to stop making sand is as valuable as the ability to tell it to start making sand.