Most guitarists that record anythign below drop D tuning use something called a baritone 6 string... It's a guitar with a longer scale than a regular 6 string... It allows you to use higher gauge strings and to tune them lower.

Drop B tuning witha standard 6 string would require A LOT of tweeking of your guitar... So I personally wouldn't recommend it unless you get a guitar that you can just keep in drop B tuning all the time.