I was skeptical at first too so I went to a local grocery store and got a 3 gallon bucket. Drilled a hole for a stopper and put an airlock on it. All for less than a couple of bucks. Now I have a 5 gallon batch going...about 3 months now and plan to age another 3 months. I would say you are ok on the headspace for primary, but if you start getting into the wines and want to age them, you will need to eliminate the headspace when you rack to secondary to get it off the sediment. But you could just do a 3 month or shorter primary and then bottle to test it out.