The RBA section of the Subtank is pretty nice, and it's nifty because if you're in a pinch you can just switch back to the OCC head and call it a day. Imo, ideal tank to bring on vacation solely for the dual functionality. Pack of OCC heads and your RBA section/spare wick and you're good to go, worst case scenario you destroy your RBA coil re-wicking or something, just throw an OCC head in there.