You don't need to do a full restore to fix the issue. I did the OTA update and lost service/touch ID. I then downloaded the ISPW and did an option check for update. iTunes then installed 8.0.1 again without needing to restore my data.
iPhone 6 http://appldnld.apple.com/iOS8/031-07540.20140924.b41vK/iPhone7,2_8.0.1_12A402_Restore.ipsw
iPhone 6+ http://appldnld.apple.com/iOS8/031-07519.20140924.FTHpb/iPhone7,1_8.0.1_12A402_Restore.ipsw
Can i ask how you did this exactly? You downloaded the IPSW, I've got that now. then from iTunes you did hold down option/restore, and selected the IPSW you downloaded?