If you own one high end server and one low end server. Meaning they are paid for and sitting in your workplace. How does one server operate cheaper than the other? Draws 3 less Kw/h a week in electricity? Seems rather insignificant. Not to mention you'd have to dedicate a team to switching over the data and making sure it goes smoothly for a month prior with preliminary testing. Not to mention they are improving the game, meaning they want more people to play/return. So then if they did "downgrade" server they'd just have to reassign the same team again, test out for a month again. Have more downtime. Really now?
This isn't entirely true. If the servers are what I'm thinking they are, they're just executables that call a separate database server that most likely runs different databases on its own. In that case you'd simply install the server on a different machine, copy over the config, and point it at the correct database. On a powerful enough machine this can even be set up in an array of virtual machines with several game servers running on the same hardware, all pointed to their respective databases ( or even possibly the same database).
**** it might be running on an old Pentium II Compaq as far as we know.