Yes, it can be switch back but make sure U follow the steps and save yr current rom.
Since it's password is not a secret and to save internet resourse, the login/pass is "xda". for direct link, try Here
As Kevin said already, this method require some technical skills (eg. hex edit) and there is a risk that Rom get corrupt and cannot be boot. Do it as yr own risk and make sure U follow the steps carefully.
My SE X1 rom-> http://forum.xda-developers.com/forumdisplay.php?f=471