The lack of a 6.5g (or 7g, while we are dreaming) is the only thing that prevents me from going with the BB.
We don't have to many rules in my house, but one of those rules is that we don't waste beer.
Even for a blow-off tube.
I contacted The Barrel Mill, alleged supplier to Cigar City. They have commercial size spirals, but these won't fit in a carboy. I'm guessing that if you broke it into pieces you could fit it in a bucket, though.
I was listening to a Brew Strong podcast, in which Jamil Zainasheff and John Palmer talked about wax. It was in the series about bottling/kegging of podcasts they did some time in 2009 (I think). They mentioned that not much is available about the oxygen permeability of wax.
It seems like a...