It works for me, however this is from their AUP:
Will I be billed if I exceed these allowances?
Cox does not currently charge you additional fees if you exceed your allowance. If you determine that your Internet data usage will continue to exceed your allowance, we recommend that you consider a Cox High Speed Internet package that more closely matches your use of the service. If you are consistently going over your data usage allowance, you will also benefit from the faster speeds that come with a higher Internet package.
So just remember that - metered billing is coming, however, at least for now, there doesn't seem to be any enforcement if you go over your cap.. I wouldn't worry about it. If I backup my entire music directory, they would probably be like what is he doing?
is starting to help us customers stop cox from doing the metered billing but, for now - the cap is just there to get us used to it..