I have asked the same question on this and another forum. I have been told no. The bootloader is different and it will brick your phone if you do it. That's just what I was told.
I know Matt's 1.7 Utility can "fix" a failed sideload of .211 but I don't know of anyone who has reverted back to GB after a successful ICS upgrade.
I really dont think there will be a way back to GB. they have been trying this for months now with no luck. only thing they were able to do was save peoples bricked phones.
Sorry dude but I think your stuck with ICS. I am curious, what is it that you dont like about ICS?? its far better than GB.
why would you want to go back for at the most a week and then be back on ics again? Unless there is a way to stop getting the update?