How on earth do you move a 12-gallon glass carboy that's full of wort? You buy a folklift on Craigslist, too? Those things have got to weight what, fifty pounds just empty?
To answer the question - they should work, you just might need a blow-off tube depending on your actual volume and how aggressive a ferment you have. I ferment 5 gallons in a 6 gallon BB, that's the same math at 10 gallons in a 12.