Wow... With that varying cost, I can afford to move 5-6 toons off of my regular servers to the one I'm currently playing on for the price of moving 3 chars at the regular rate!
What a bargain!
Nice idea, but won't be implemented.
Someone would have to acknowledge there was a server population issue on some of the servers in the first place, let alone start classifying them into those three categories.
Creative thinking, tho!