The head space in a bucket is far too much for secondary. In a carboy, you have maybe an inch wide area that is open. You still have a bung, but it's about an inch wide where there is a possiblity for oxidation. That's really good, and you won't taste any oxidation. The headspace for a bucket is as wide as the bucket- not good at all. Even if you fill the bucket to the top, the headspace could be 12 inches across, and it will ruin the mead.
Broken Leg Brewery
Giving beer a leg to stand on since 2006