Default [Q] Question on reverting back to stock

I have Verizon G2 running Malladus and TWRP ....3 recovery and also took the 12B update. I have had recurring issues with GPS and MMS and want to try and revert back to stock. I have a stock backup made on the previous firmware (11A as I recall). Can I restore this backup if I took the 12B update? Also will I get any update warnings after I restore and anything I should clearly avoid to prevent a brick?