I hope that they can figure something out cause I really like this ROM! I love my music though but not having any enhancer really takes away from it. I would go back to a GB ROM but getting the old mainver back looks a little scary.
I think that if you want to go back to GB and not have to worry about mainver, just use the latest RUU?
I think that does a complete format and restore of the phone to it's true out of the box state and should wipe out anything from an ICS ROM without trouble.
I have tried a few ICS ROMS and used the RUU method to roll back and not had any issues. I create a Nandroid before trying ICS, and so if I have to RUU, I do that, unlock and root it, install Amon Ra and then restore my Nandroid and I am back where I started in half hour or less.