Originally Posted by Cayuga
As a bigger winemaker than brewer, please don't mix your buckets. You'll get off tastes either direction. You make beer to taste beer, wine for wine. I know that space can be an issue, you should see my lack of space, but I always keep them separated. And do you usually brew 6 gallon batches? 1 gallon of headspace seems alot to me, but I am still learning.
I've made well over two hundred batches of beer, and probably that many in wine. I don't yet have any off-flavors from mixing my equipment. Are you sure that's a certainty? If you clean your equipment properly, so that there are no odors or stains, why can't you mix the equipment?
Headspace is crucial after primary for winemaking, but not so much for beer. I think it would be more important in "big" beers that age for a while, like a barley wine or imperial stout, so you could reduce the headspace for something that will sit a while. I've been skipping secondary altogether in many beers, so the issue of headspace doesn't even come up with most ales.