After reading this thread, i realized most people don't understand the 'feature', and think they have to pay to play TBC... or that they'll lose everything they had on classic if they don't.
Read the friggin feature boys. Payment to CLONE your character so you can have your same character -TWICE-, on two different games!
You can stay, or go, FOR FREE!
Very few people will have any interest whatsoever in maintaining duplicate chars, and even then, it's even less of the cost of a boost, or close to a transfer!