If the phone's mail client allows you to simply change your server address, then yes, that is an easy option and doesn't cause duplication (I was able to do this on my WP7.5 device).
If a phone does not allow you to do this, then a new profile will be required (and before you ask, there is no list of devices that support this).
Have a great day,
Dan
www.insecurityinc.info