Why can't you just use the .85 update after you .181 the system, so then all bricked users will actually be at the latest ICS release?
I don't understand all the tech reasons but it has been tried and it does not work.
It's due to that pesky bootloader not letting you go back. So, you can fix your phone with this method if you are soft-bricked with either of the 84/85 leaks but there isn't a way to manipulate the bootloader to flash back to the GB releases. Once the official ICS OTA comes out, I don't think there will be as many people wanting to flash back to GB.